(11 January 99)

Molecule, basis, wavefunction specification:

$CONTRL chemical control data INPUTA: START

$SYSTEM computer related control data INPUTA: START

$BASIS basis set INPUTB: BASISS

$DATA molecule, basis set INPUTB: MOLE

$ZMAT coded z-matrix ZMATRX: ZMATIN

$LIBE linear bend data ZMATRX: LIBE

$SCF HF-SCF wavefunction control SCFLIB: SCFIN

$SCFMI SCF-MI input control data SCFMI :MIINP

$MP2 2nd order Moller-Plesset MP2: MP2INP

$GUESS initial orbital selection GUESS: GUESMO

$VEC orbitals (formatted) GUESS: READMO

Potential energy surface options:

$STATPT geometry search control STATPT: SETSIG

$TRUDGE nongradient optimization TRUDGE: TRUINP

$TRURST restart data for TRUDGE TRUDGE: TRUDGX

$FORCE hessian, normal coordinates HESS: HESSX

$CPHF coupled-Hartree-Fock options CPHF: CPINP

$HESS force constant matrix (formatted) HESS: FCMIN

$GRAD gradient vector (formatted) HESS: EGIN

$DIPDR dipole deriv. matrix (formatted) HESS: DDMIN

$VIB HESSIAN restart data (formatted) HESS: HSSNUM

$MASS isotope selection VIBANL:RAMS

$IRC intirisic reaction path RXNCRD:IRCX

$DRC dynamic reaction path DRC: DRCDRV

$SURF potential surface scan SURF :SRFINP

Interpretation, properties:

$LOCAL orbital localization control LOCAL: LMOINP

$TWOEI J,K integrals (formatted) LOCCD: TWEIIN

$ELMOM electrostatic moments PRPLIB: INPELM

$ELPOT electrostatic potential PRPLIB: INPELP

$ELDENS electron density PRPLIB: INPELD

$ELFLDG electric field/gradient PRPLIB: INPELF

$POINTS property calculation points PRPLIB: INPPGS

$GRID property calculation mesh PRPLIB: INPPGS

$PDC MEP fitting mesh PRPLIB: INPPDC

$MOLGRF orbital plots PARLEY:PLTMEM

$STONE distributed multipole analysis PRPPOP: STNRD

$MOROKM Morokuma energy decomposition MOROKM:MOROIN

$FFCALC finite electric field FFIELD: FFLDX

$TDHF time dependent HF NLO properties TDHF: TDHFX

Solvation models:

$EFRAG effective fragment potentials EFINP:EFINP

$FRAGNAME specific named fragment pot. EFINP:RDSTFR

$FRGRPL inter-fragment repulsion EFINP:RDDFRL

$PCM polarizable continuum model PCM :PCMINP

$PCMCAV PCM cavity generation PCM :MAKCAV

$NEWCAV PCM escaped charge cavity PCM :DISREP

$DISBS PCM dispersion basis set PCMDIS:ENLBS

$DISREP PCM dispersion/repulsion PCMVCH:MORETS

$SCRF self consistent reaction field SCRF:ZRFINP

Integral and integral modification options:

$ECP effective core potentials ECPLIB:ECPPAR

$EFIELD external electric field PRPLIB:INPEF

$INTGRL format for 2e- integrals INPUTA:START

$TRANS integral transformation TRFIN :TRANS

MCSCF and CI wavefunctions, and their properties:

$CIINP control of CI process GAMESS:WFNCI

$DET determinantal full CI for MCSCF ALDECI:DETINP

$CIDET determinantal full CI ALDECI:DETINP

$DRT distinct row table for MCSCF GUGDRT:ORDORB

$CIDRT distinct row table for CI GUGDRT:ORDORB

$MCSCF parameters for MCSCF MCSCF :MCSCF

$MCQDPT multireference pert. Theory MCQDPT:MQREAD

$CISORT integral sorting GUGSRT:GUGSRT

$GUGEM Hamiltonian matrix formation GUGEM :GUGAEM

$GUGDIA Hamiltonian eigenvalues/vectors GUGDGA:GUGADG

$GUGDM 1e- density matrix GUGDM :GUGADM

$GUGDM2 2e- density matrix GUGDM2:GUG2DM

$LAGRAN CI lagrangian matrix LAGRAN:CILGRN

$TRFDM2 2e- density backtransformation TRFDM2:TRF2DM

$TRANST transition moments, spin-orbit TRNSTN:TRNSTX

* this column is more useful to programmers than to users.

$CONTRL group (optional)

This is a free format group specifying global switches.

SCFTYPtogether with MPLEVL or CITYP specifies the wavefunction. You may choose from:

= RHFRestricted Hartree Fock calculation (default)

= UHFUnrestricted Hartree Fock calculation

= ROHFRestricted open shell Hartree-Fock. (high spin, see GVB for low spin)

= GVBGeneralized valence bond wavefunction or OCBSE type ROHF. (needs $SCF input)

= MCSCFMulticonfigurational SCF wavefunction (this requires $DET or $DRT input)

= NONEindicates a single point computation, rereading a converged SCF function. This option requires that you select CITYP=GUGA or ALDET, RUNTYP=ENERGY, TRANSITN, or SPINORBT, and GUESS=MOREAD.

MPLEVL = chooses Moller-Plesset perturbation theory level, after the SCF.

= 0 skips the MP computation (default)

= 2performs a second order energy correction. MP2 is implemented only for for RHF, UHF, ROHF, and MCSCF wavefunctions. Gradients are available only for RHF, so for the others you may pick from RUNTYP=ENERGY, TRUDGE, SURFACE, or FFIELD only.

CITYP = chooses CI computation after the SCF. Any SCFTYP except UHF may be followed by a CI computation.

= NONE skips the CI. (default)

= GUGAruns the Unitary Group CI package, which requires $CIDRT input. Gradients are available only for RHF, so for other SCFTYPs, you may choose only RUNTYP=ENERGY, TRUDGE, SURFACE, FFIELD, TRANSITN, or SPINORBT.

= ALDETruns the Ames Laboratory determinant full CI package, requiring $CIDET input. RUNTYP=ENERGY only.

Obviously, at most one of MPLEVL or CITYP may be chosen.

RUNTYP specifies the type of computation, for example at a single geometry point:

= ENERGY Molecular energy. (default)

= GRADIENT Molecular energy plus gradient.

= HESSIANMolecular energy plus gradient plus second derivatives, including harmonic vibrational analysis. See the $FORCE input group.

multiple geometry options:

= OPTIMIZEOptimize the molecular geometry using analytic energy gradients. See $STATPT.

= TRUDGENon-gradient total energy minimization. See groups $TRUDGE and $TRURST.

= SADPOINTLocate saddle point (transition state). See the $STATPT group.

= IRC Follow intrinsic reaction coordinate. See the $IRC group.

= GRADEXTR Trace gradient extremal. See the $GRADEX group.

= DRC Follow dynamic reaction coordinate. See the $DRC group.

= SURFACEScan linear cross sections of the potential energy surface. See $SURF.

single geometry property options:

= PROPProperties will be calculated. A $DATA deck and converged $VEC group should be input. Optionally, orbital localization can be done. See $ELPOT, etc.

= MOROKUMAPerforms monomer energy decomposition. See the $MOROKM group.

= TRANSITNCompute radiative transition moment. See the $TRANST group.

= SPINORBT Compute spin-orbit coupling. See the $TRANST group.

= FFIELDapplies finite electric fields, most commonly to extract polarizabilities. See the $FFCALC group.

= TDHFanalytic computation of time dependent polarizabilities. See the $TDHF group.

Note that RUNTYPs involving the energy gradient, which are GRADIENT, HESSIAN, OPTIMIZE, SADPOINT, IRC, GRADEXTR, and DRC, cannot be used for any CI or MP2 computation, except when SCFTYP=RHF.

EXETYP = RUN Actually do the run. (default)

= CHECKWavefunction and energy will not be evaluated. This lets you speedily check input and memory requirements. See the overview section for details.

= DEBUGMassive amounts of output are printed, useful only if you hate trees.

= routineMaximum output is generated by the routine named. Check the source for the routines this applies to.

MAXIT = Maximum number of SCF iteration cycles. Pertains only to RHF, UHF, ROHF, or GVB runs. See also MAXIT in $MCSCF. (default = 30)

ICHARG = Molecular charge. (default=0, neutral)

MULT = Multiplicity of the electronic state

= 1 singlet (default)

= 2,3,... doublet, triplet, and so on.

ICHARG and MULT are used directly for RHF, UHF, ROHF. For GVB, these are implicit in the $SCF input, while for MCSCF or CI, these are implicit in $DRT/$CIDRT or $DET/$CIDET input. You must still give them correctly here.

ECP = effective core potential control.

= NONE all electron calculation (default).

= READ read the potentials in $ECP group.

= SBKJCuse Stevens, Basch, Krauss, Jasien, Cundari potentials for all heavy atoms (Li-Rn are available).

= HWuse Hay, Wadt potentials for all the heavy atoms (Na-Xe are available).

* * * the next three control molecular geometry * * *

COORD = choice for molecular geometry in $DATA.

= UNIQUEonly the symmetry unique atoms will be given, in Cartesian coords (default).

= HINTonly the symmetry unique atoms will be given, in Hilderbrandt style internals.

= CARTCartesian coordinates will be input. Please read the warning just below!!!

= ZMT GAUSSIAN style internals will be input.

= ZMTMPC MOPAC style internals will be input.

= FRAGONLYmeans no part of the system is treated by ab initio means, hence $DATA is not given. The system is specified by $EFRAG.

Note that the CART, ZMT, ZMTMPC choices require input of all atoms in the molecule. These three also orient the molecule, and then determine which atoms are unique. The reorientation is very likely to change the order of the atoms from what you input. When the point group contains a 3-fold or higher rotation axis, the degenerate moments of inertia often cause problems choosing correct symmetry unique axes, in which case you must use COORD=UNIQUE rather than Z-matrices.

Warning: The reorientation into principal axes is done only for atomic coordinates, and is not applied to the axis dependent data in the following groups: $VEC, $HESS, $GRAD, $DIPDR, $VIB, nor Cartesian coords of effective fragments in $EFRAG. COORD=UNIQUE avoids reorientation, and thus is the safest way to read these.

Note that the choices CART, ZMT, ZMTMPC require the use of a $BASIS group to define the basis set. The first two choices might or might not use $BASIS, as you wish.

UNITS = distance units, any angles must be in degrees.

= ANGS Angstroms (default)

= BOHR Bohr atomic units

NZVAR = 0 Use Cartesian coordinates (default).

= MIf COORD=ZMT or ZMTMPC and a $ZMAT is not given: the internal coordinates will be those defining the molecule in $DATA. In this case, $DATA must not contain any dummy atoms. M is usually 3N-6, or 3N-5 for linear.

= MFor other COORD choices, or if $ZMAT is given: the internal coordinates will be those defined in $ZMAT. This allows the use of more sophisticated internal coordinate choices. M is ordinarily 3N-6 (3N-5), unless $ZMAT has linear bends.

NZVAR refers mainly to the coordinates used by OPTIMIZE or SADPOINT runs, but may also print the internal's values for other run types. You can use internals to define the molecule, but Cartesians during optimizations!

LOCAL = controls orbital localization.

= NONE Skip localization (default).

= BOYS Do Foster-Boys localization.

= RUEDNBRG Do Edmiston-Ruedenberg localization.

= POP Do Pipek-Mezey population localization.

See the $LOCAL group. Localization does not work for SCFTYP=GVB or CITYP.

* * * interfaces to other programs * * *

MOLPLT =flag that produces an input deck for a molecule drawing program distributed with GAMESS. (default is .FALSE.)

PLTORB =flag that produces an input deck for an orbital plotting program distributed with GAMESS. (default is .FALSE.)

AIMPAC =flag to create an input deck for Bader's atoms in molecules properties code. (default=.FALSE.)

For information about this program, contact

Richard F.W. Bader

Dept. of Chemistry

McMaster University

Hamilton, Ontario L8S-4M1 Canada

bader@sscvax.cis.mcmaster.ca

RPAC =flag to create the input files for Bouman and Hansen's RPAC electronic excitation and NMR shieldings program. RPAC works only with RHF wavefunctions. Contact Prof. Aage Hansen in Copenhagen (nahaeh@vm.uni-c.dk) about this program. (default is .FALSE.)

FRIEND = string to prepare input to other quantum programs, choose from

= HONDO for HONDO 8.2

= MELDF for MELDF

= GAMESSUK for GAMESS (UK Daresbury version)

= GAUSSIAN for Gaussian 9x

= ALL for all of the above

PLTORB, MOLPLT, and AIMPAC decks are written to file PUNCH at the end of the job. The two binary disk files output by RPAC are written at the end of the job. Thus all of these correspond to the final geometry encountered during the job.

In contrast, selecting FRIEND turns the job into a CHECK run only, no matter how you set EXETYP. Thus the geometry is that encountered in $DATA. The input is added to the PUNCH file, and may require some (usually minimal) massaging.

PLTORB and MOLPLT are written even for EXETYP=CHECK. AIMPAC requires at least RUNTYP=PROP. RPAC requires at least RUNTYP=ENERGY, and you must take action to save the binary files AOINTS and WORK15.

The NBO program of Frank Weinhold's group can be attached to GAMESS. The input to control the natural bond order analysis is read by the add in code, so is not described here. The NBO program is available by anonymous FTP to ftp.osc.edu, in the directory /pub/chemistry/software/SOURCES/FORTRAN/nbo

* * * computation control switches * * *

For the most part, the default is the only sensible value, and unless you are sure of what you are doing, these probably should not be touched.

NPRINT =Print/punch control flag See also EXETYP for debug info. (options -7 to 5 are primarily debug)

= -7 Extra printing from Boys localization.

= -6 debug for geometry searches

= -5 minimal output

= -4 print 2e-contribution to gradient.

= -3 print 1e-contribution to gradient.

= -2 normal printing, no punch file

= 1 extra printing for basis,symmetry,ZMAT

= 2 extra printing for MO guess routines

= 3 print out property and 1e- integrals

= 4 print out 2e- integrals

= 5 print out SCF data for each cycle.

(Fock and density matrices, current MOs

= 6same as 7, but wider 132 columns output.

= 7 normal printing and punching (default)

= 8more printout than 7. The extra output is (AO) Mulliken and overlap population analysis, eigenvalues, Lagrangians,

= 9everything in 8 plus Lowdin population analysis, final density matrix.

NOSYM = 0the symmetry specified in $DATA is used as much as possible in integrals, SCF, gradients, etc. (this is the default)

= 1the symmetry specified in the $DATA group is used to build the molecule, then symmetry is not used again. Some GVB or MCSCF runs (those without a totally symmetric charge density) require you request no symmetry.

INTTYP =POPLE use fast Pople routines for sp integral blocks, and HONDO Rys polynomial code for all other integrals. (default)

=HONDO use HONDO/Rys integrals for all integrals. This option produces slightly more accurate integrals but is also slower.

NORMF = 0 normalize the basis functions (default)

= 1 no normalization

NORMP = 0input contraction coefficients refer to normalized Gaussian primitives. (default)

= 1 the opposite.

ITOL = primitive cutoff factor (default=20)

= nproducts of primitives whose exponential factor is less than 10**(-n) are skipped.

ICUT = nintegrals less than 10.0**(-n) are not saved on disk. (default = 9)

* * * restart options * * *

IREST =restart control options (for OPTIMIZE run restarts, see $STATPT) Note that this option is unreliable!

= -1reuse dictionary file from previous run, useful with GEOM=DAF and/or GUESS=MOSAVED. Otherwise, this option is the same as 0.

= 0 normal run (default)

= 1 2e restart (1-e integrals and MOs saved)

= 2 SCF restart (1-,2-e integrals and MOs saved)

= 3 1e gradient restart

= 4 2e gradient restart

GEOM = select where to obtain molecular geometry

= INPUT from $DATA input (default for IREST=0)

= DAF read from DICTNRY file (default otherwise)

As noted in the first chapter, binary file restart is not a well tested option!

$SYSTEM group (optional)

This group provides global control information for your computer's operation. This is system related input, and will not seem particularly chemical to you!

TIMLIM =time limit, in minutes. Set to about 95 percent of the time limit given to the batch job so that GAMESS can stop itself gently. (default=600.0)

MEMORY =establishes the maximum memory which your job can use. Some systems allocate just this amount dynamically, others impose a static upper limit. The default causes allocation of a system dependent, moderate amount. For many systems this amount is 750,000 words. (default=0)

KDIAG = diagonalization control switch

= 0use a vectorized diagonalization routine if one is available on your machine, else use EVVRSP. (default)

= 1use EVVRSP diagonalization. This may be more accurate than KDIAG=0.

= 2use GIVEIS diagonalization (not as fast or reliable as EVVRSP)

= 3use JACOBI diagonalization (this is the slowest method)

COREFL =a flag to indicate whether or not GAMESS should produce a "core" file for debugging when subroutine ABRT is called to kill a job. This variable pertains only to UNIX operating systems. (default=.FALSE.)

* * * the next three refer to parallel GAMESS * * *

BALTYP =parallel load balance scheme for integral sections. Choose LOOP to pick the inner most loop for parallelization, and NXTVAL to parallelize near the outer loop. The best strategy for equal speed processors is LOOP, whereas NXTVAL will give better load balance for mixed processors. The default is NXTVAL on machines using TCGMSG.

XDR =a flag to indicate whether or not messages should be converted into a generic format known as external data representation. If true, messages can exchange between machines of different vendors, at the cost of performing the data type conversions. (default=.FALSE.)

On machines which do not use TCGMSG (the IBM SP, the Intel Paragon, the CM-5), the BALTYP and XDR variables are ignored. LOOP balancing is used exclusively, and there is no possible transfer of data to another vendor so XDR is irrelevant.

PTIME =a logical flag to print extra timing info during parallel runs. This is not currently implemented.

$BASIS group (optional)

This group allows certain standard basis sets to be easily given. If this group is omitted, the basis set must be given instead in the $DATA group.

GBASIS = Name of the Gaussian basis set.

= MINI Huzinaga's 3 gaussian minimal basis set. Available H-Rn.

= MIDI Huzinaga's 21 split valence basis set. Available H-Xe.

= STO Pople's STO-NG minimal basis set.

Available H-Xe, for NGAUSS=2,3,4,5,6.

= N21 Pople's N-21G split valence basis set.

Available H-Xe, for NGAUSS=3.

Available H-Ar, for NGAUSS=6.

= N31 Pople's N-31G split valence basis set.

Available H-Ne,P-Cl for NGAUSS=4.

Available H-He,C-F for NGAUSS=5.

Available H-Ar, for NGAUSS=6.

For Ga-Kr, N31 selects the BC basis.

= N311 Pople's "triple split" N-311G basis set.

Available H-Ne, for NGAUSS=6.

Selecting N311 implies MC for Na-Ar.

= DZV "double zeta valence" basis set.

a synonym for DH for H,Li,Be-Ne,Al-Cl.

a synonym for BC for Ga-Kr.

= DH Dunning/Hay "double zeta" basis set.

(3s)/[2s] for H.

(9s,4p)/[3s,2p] for Li.

(9s,5p)/[3s,2p] for Be-Ne.

(11s,7p)/[6s,4p] for Al-Cl.

= BC Binning/Curtiss "double zeta" basis set.

(14s,11p,5d/[6s,4p,1d] for Ga-Kr.

= TZV "triple zeta valence" basis set.

(5s)/[3s] for H.

(10s,3p)/[4s,3p] for Li.

(10s,6p)/[5s,3p] for Be-Ne.

a synonym for MC for Na-Ar.

(14s,9p)/[8s,4p] for K-Ca.

(14s,11p,6d)/[10s,8p,3d] for Sc-Zn.

= MC McLean/Chandler "triple split" basis.

(12s,9p)/[6s,5p] for Na-Ar.

Selecting MC implies 6-311G for H-Ne.

* * * the next two are ECP bases only * * *

GBASIS = SBKJCStevens/Basch/Krauss/Jasien/Cundari valence basis set, for Li-Rn. This choice implies an unscaled -31G basis for H-He.

= HWHay/Wadt valence basis. This is a -21 split, available NaXe, except for the transition metals. This implies a 3-21G basis for H-Ne.

* * * semiempirical basis sets * * *

The elements for which these exist can be found in the 'further information' section of this manual. If you pick one of these, all other data in this group is ignored.

GBASIS = MNDO selects MNDO model hamiltonian

= AM1 selects AM1 model hamiltonian

= PM3 selects PM3 model hamiltonian

NGAUSS =the number of Gaussians (N). This parameter pertains only to GBASIS=STO, N21, N31, or N311.

NDFUNC =number of heavy atom polarization functions to be used. These are usually d functions, except for MINI/MIDI. The term "heavy" means Na on up when GBASIS=STO, HW, or N21, and from Li on up otherwise. The value may not exceed 3. The variable POLAR selects the actual exponents to be used, see also SPLIT2 and SPLIT3. (default=0)

NFFUNC =number of heavy atom f type polarization functions to be used on Li-Cl. This may only be input as 0 or 1. (default=0)

NPFUNC =number of light atom, p type polarization functions to be used on H-He. This may not exceed 3, see also POLAR. (default=0)

DIFFSP =flag to add diffuse sp (L) shell to heavy atoms. Heavy means Li-F, Na-Cl, Ga-Br, In-I, Tl-At. The default is .FALSE.

DIFFS = flag to add diffuse s shell to hydrogens. The default is .FALSE.

POLAR = exponent of polarization functions

= POPLE (default for all other cases)

= POPN311 (default for GBASIS=N311, MC)

= DUNNING (default for GBASIS=DH, DZV)

= HUZINAGA (default for GBASIS=MINI, MIDI)

= HONDO7 (default for GBASIS=TZV)

SPLIT2 =an array of splitting factors used when NDFUNC or NPFUNC is 2. Default=2.0,0.5

SPLIT3 =an array of splitting factors used when NDFUNC or NPFUNC is 3. Default=4.00,1.00,0.25

The splitting factors are from the Pople school, and are probably too far apart. See for example the Binning and Curtiss paper. For example, the SPLIT2 value will usually cause an INCREASE over the 1d energy at the HF level for hydrocarbons.

The actual exponents used for polarization functions, as well as for diffuse sp or s shells, are described in the 'Further References' section of this manual. This section also describes the sp part of the basis set chosen by GBASIS fully, with all references cited.

Note that GAMESS always punches a full $DATA group. Thus, if $BASIS does not quite cover the basis you want, you can obtain this full $DATA group from EXETYP=CHECK, and then change polarization exponents, add Rydbergs, etc.

$DATA group (required)

This group describes the global molecular data such as point group symmetry, nuclear coordinates, and possibly the basis set. It consists of a series of free format card images.

-1- TITLE a single descriptive title card.

-2- GROUP, NAXIS

GROUP is the Schoenflies symbol of the symmetry group, you may choose from C1, CS, CI, CN, S2N, CNH, CNV, DN, DNH, DND, T, TH, TD, O, OH.

NAXIS is the order of the highest rotation axis, and must be given when the name of the group contains an N. For example, "CNV 2" is C2v. "S2n 3" means S6.

For linear molecules, choose either CNV or DNH, and enter NAXIS as 4. Enter atoms as DNH with NAXIS=2. If the electronic state of either is degenerate, check the note about the effect of symmetry in the electronic state in the SCF section of REFS.DOC.

In order to use GAMESS effectively, you must be able to recognize the point group name for your molecule. This presupposes a knowledge of group theory at about the level of Cotton's "Group Theory", Chapter 3.

Armed with only the name of the group, GAMESS is able to exploit the molecular symmetry throughout almost all of the program, and thus save a great deal of computer time. GAMESS does not require that you know very much else about group theory, although a deeper knowledge (character tables, irreducible representations, term symbols, and so on) is useful when dealing with the more sophisticated wavefunctions.

Cards -3- and -4- are quite complicated, and are rarely given. A *SINGLE* blank card may replace both cards -3- and -4-, to select the 'master frame', which is defined on the next page. If you choose to enter a blank card, skip to the bottom of the next page.

Note! If the point group is C1 (no symmetry), skip over cards -3- and -4- (which means no blank card).

-3- X1, Y1, Z1, X2, Y2, Z2

For C1 group, there is no card -3- or -4-.

For CI group, give one point, the center of inversion.

For CS group, any two points in the symmetry plane.

For axial groups, any two points on the principal axis.

For tetrahedral groups, any two points on a two-fold axis.

For octahedral groups, any two points on a four-fold axis.

-4- X3, Y3, Z3, DIRECT

third point, and a directional parameter.

For CS group, one point of the symmetry plane, noncollinear with points 1 and 2.

For CI group, there is no card -4-.

For other groups, a generator sigma-v plane (if any) is the (x,z) plane of the local frame (CNV point groups).

A generator sigma-h plane (if any) is the (x,y) plane of the local frame (CNH and dihedral groups).

A generator C2 axis (if any) is the x-axis of the local frame (dihedral groups).

The perpendicular to the principal axis passing through the third point defines a direction called D1. If DIRECT='PARALLEL', the x-axis of the local frame coincides with the direction D1. If DIRECT='NORMAL', the x-axis of the local frame is the common perpendicular to D1 and the principal axis, passing through the intersection point of these two lines. Thus D1 coincides in this case with the negative y axis.

The 'master frame' is just a standard orientation for the molecule. By default, the 'master frame' assumes that

1. z is the principal rotation axis (if any),

2. x is a perpendicular two-fold axis (if any),

3. xz is the sigma-v plane (if any), and

4. xy is the sigma-h plane (if any).

Use the lowest number rule that applies to your molecule.

Some examples of these rules:

Ammonia (C3v): the unique H lies in the XZ plane (R1,R3).

Ethane (D3d): the unique H lies in the YZ plane (R1,R2).

Methane (Td): the H lies in the XYZ direction (R2). Since

there is more than one 3-fold, R1 does not apply.

HP=O (Cs): the mirror plane is the XY plane (R4).

In general, it is a poor idea to try to reorient the molecule. Certain sections of the program, such as the orbital symmetry assignment, do not know how to deal with cases where the 'master frame' has been changed.

Linear molecules (C4v or D4h) must lie along the z axis, so do not try to reorient linear molecules.

You can use EXETYP=CHECK to quickly find what atoms are generated, and in what order. This is typically necessary in order to use the general $ZMAT coordinates.

Depending on your choice for COORD in $CONTROL,

if COORD=UNIQUE, follow card sequence U

if COORD=HINT, follow card sequence U

if COORD=CART, follow card sequence C

if COORD=ZMT, follow card sequence G

if COORD=ZMTMPC, follow card sequence M

Card sequence U is the only one which allows you to define a completely general basis here in $DATA.

Recall that UNIT in $CONTRL determines the distance units.

-5U- Atom input. Only the symmetry unique atoms are input, GAMESS will generate the symmetry equivalent atoms according to the point group selected above.

if COORD=UNIQUE NAME, ZNUC, X, Y, Z

NAME =10 character atomic name, used only for printout. Thus you can enter H or Hydrogen, or whatever.

ZNUC =nuclear charge. It is the nuclear charge which actually defines the atom's identity.

X,Y,Z = Cartesian coordinates.

if COORD=HINT

NAME,ZNUC,CONX,R,ALPHA,BETA,SIGN,POINT1,POINT2,POINT3

NAME = 10 character atomic name (used only for print out).

ZNUC = nuclear charge.

CONX = connection type, choose from

'LC' linear conn. 'CCPA' central conn.

'PCC' planar central conn. with polar atom

'NPCC' non-planar central conn. 'TCT' terminal conn.

'PTC' planar terminal conn. with torsion

R = connection distance.

ALPHA= first connection angle

BETA = second connection angle

SIGN = connection sign, '+' or '-'

POINT1, POINT2, POINT3 =

connection points, a serial number of a previously input atom, or one of 4 standard points: O,I,J,K (origin and unit points on axes of master frame). defaults: POINT1='O', POINT2='I', POINT3='J'

ref- R.L. Hilderbrandt, J.Chem.Phys. 51, 1654 (1969).

You cannot understand HINT input without reading this.

Note that if ZNUC is negative, the internally stored basis for ABS(ZNUC) is placed on this center, but the calculation uses ZNUC=0 after this. This is useful for basis set superposition error (BSSE) calculations.

* * * If you gave $BASIS, continue entering cards -5U- until all the unique atoms have been specified. When you are done, enter a " $END " card.

* * * If you did not, enter cards -6U-, -7U-, -8U-.

-6U- GBASIS, NGAUSS, (SCALF(i),i=1,4)

GBASIS has exactly the same meaning as in $BASIS. You may choose from MINI, MIDI, STO, N21, N31, N311, DZV, DH, BC, TZV, MC, SBKJC, or HW. In addition, you may choose S, P, D, F, G, or L to enter an explicit basis set. Here, L means an s and p shell with a common exponent.

NGAUSS is the number of Gaussians (N) in the Pople style basis, or user input general basis. It has meaning only for GBASIS=STO, N21, N31, or N311, and S,P,D,F,G, or L.

Up to four scale factors may be entered. If omitted, standard values are used. They are not documented as every GBASIS treats these differently. Read the source code if you need to know more. They are seldom given.

* * *If GBASIS is not S,P,D,F,G, or L, either add more shells by repeating card 6U-, or go on to -8U-.

* * * If GBASIS=S,P,D,F,G, or L, enter NGAUSS cards -7U-.

-7U- IG, ZETA, C1, C2

IG = a counter, IG takes values 1, 2, ..., NGAUSS.

ZETA = Gaussian exponent of the IG'th primitive.

C1= Contraction coefficient for S,P,D,F,G shells, and for the s function of L shells.

C2 = Contraction coefficient for the p in L shells.

* * * For more shells on this atom, go back to card -6U-.

* * * If there are no more shells, go on to card -8U-.

-8U- A blank card ends the basis set for this atom.

Continue entering atoms with -5U- through -8U- until all are given, then terminate the group with a " $END " card.

--- this is the end of card sequence U ---

COORD=CART input:

-5C- Atom input.

Cartesian coordinates for all atoms must be entered. They may be arbitrarily rotated or translated, but must possess the actual point group symmetry. GAMESS will reorient the molecule into the 'master frame', and determine which atoms are the unique ones. Thus, the final order of the atoms may be different from what you enter here.

NAME, ZNUC, X, Y, Z

NAME =10 character atomic name, used only for printout. Thus you can enter H or Hydrogen, or whatever.

ZNUC =nuclear charge. It is the nuclear charge which actually defines the atom's identity.

X,Y,Z = Cartesian coordinates.

Continue entering atoms with card -5C- until all are given, and then terminate the group with a " $END " card.

--- this is the end of card sequence C ---

COORD=ZMT input: (GAUSSIAN style internals)

-5G- ATOM

Only the name of the first atom is required.

See -8G- for a description of this information.

-6G- ATOM i1 BLENGTH

Only a name and a bond distance is required for atom 2.

See -8G- for a description of this information.

-7G- ATOM i1 BLENGTH i2 ALPHA

Only a name, distance, and angle are required for atom 3.

See -8G- for a description of this information.

-8G- ATOM i1 BLENGTH i2 ALPHA i3 BETA i4

ATOMis the chemical symbol of this atom. It can be followed by numbers, if desired, for example Si3. The chemical symbol implies the nuclear charge.

i1 defines the connectivity of the following bond.

BLENGTH is the bond length "this atom-atom i1".

i2 defines the connectivity of the following angle.

ALPHA is the angle "this atom-atom i1-atom i2".

i3 defines the connectivity of the following angle.

BETAis either the dihedral angle "this atom-atom i1- atom i2-atom i3", or perhaps a second bond angle "this atom-atom i1-atom i3".

i4defines the nature of BETA, If BETA is a dihedral angle, i4=0 (default). If BETA is a second bond angle, i4=+/-1. (sign specifies one of two possible directions).

•Repeat -8G- for atoms 4, 5, ...

•The use of ghost atoms is possible, by using X or BQ for the chemical symbol. Ghost atoms preclude the option of an automatic generation of $ZMAT.

•The connectivity i1, i2, i3 may be given as integers, 1, 2, 3, 4, 5,... or as strings which match one of the ATOMs. In this case, numbers must be added to the ATOM strings to ensure uniqueness!

•In -6G- to -8G-, symbolic strings may be given in place of numeric values for BLENGTH, ALPHA, and BETA. The same string may be repeated, which is handy in enforcing symmetry. If the string is preceded by a minus sign, the numeric value which will be used is the opposite, of course. Any mixture of numeric data and symbols may be given. If any strings were given in -6G- to -8G-, you must provide cards -9G- and 10G-, otherwise you may terminate the group now with a " $END " card.

-9G- A blank line terminates the Z-matrix section.

-10G- STRING VALUE

STRING is a symbolic string used in the Z-matrix.

VALUE is the numeric value to substitute for that string.

Continue entering -10G- until all STRINGs are defined. Note that any blank card encountered while reading -10G- will be ignored. GAMESS regards all STRINGs as variables (constraints are sometimes applied in $STATPT). It is not necessary to place constraints to preserve point group symmetry, as GAMESS will never lower the symmetry from that given at -2-. When you have given all STRINGs a VALUE, terminate the group with a " $END " card.

--- this is the end of card sequence G ---

The documentation for sequence G above and sequence M below presumes you are reasonably familiar with the input to GAUSSIAN or MOPAC. It is probably too terse to be understood very well if you are unfamiliar with these. A good tutorial on both styles of Z-matrix input can be found in Tim Clark's book "A Handbook of Computational Chemistry", published by John Wiley & Sons, 1985.

Both Z-matrix input styles must generate a molecule which possesses the symmetry you requested at -2-. If not, your job will be terminated automatically.

COORD=ZMTMPC input: (MOPAC style internals)

-5M- ATOM

Only the name of the first atom is required.

See -8M- for a description of this information.

-6M- ATOM BLENGTH

Only a name and a bond distance is required for atom 2.

See -8M- for a description of this information.

-7M- ATOM BLENGTH j1 ALPHA j2

Only a bond distance from atom 2, and an angle with respect to atom 1 is required for atom 3. If you prefer to hook atom 3 to atom 1, you must give connectivity as in -8M-.

See -8M- for a description of this information.

-8M- ATOM BLENGTH j1 ALPHA j2 BETA j3 i1 i2 i3

ATOM, BLENGTH, ALPHA, BETA, i1, i2 and i3 are as described at -8G-. However, BLENGTH, ALPHA, and BETA must be given as numerical values only. In addition, BETA is always a dihedral angle. i1, i2, i3 must be integers only.

The j1, j2 and j3 integers, used in MOPAC to signal optimization of parameters, must be supplied but are ignored here. You may give them as 0, for example.

Continue entering atoms 3, 4, 5, ... with -8M- cards until all are given, and then terminate the group by giving a " $END " card.

--- this is the end of card sequence M ---

This is the end of $DATA!

If you have any doubt about what molecule and basis set you are defining, or what order the atoms will be generated in, simply execute an EXETYP=CHECK job to find out!

$ZMAT group (required if NZVAR is nonzero in $CONTRL)

This group lets you define the internal coordinates in which the gradient geometry search is carried out. These need not be the same as the internal coordinates used in $DATA. The coordinates may be simple Z-matrix types, delocalized coordinates, or natural internal coordinates.

You must input a total of M=3N-6 internal coordinates (M=3N-5 for linear molecules). NZVAR in $CONTRL can be less than M IF AND ONLY IF you are using linear bends. It is also possible to input more than M coordinates if they are used to form exactly M linear combinations for new internals. These may be symmetry coordinates or natural internal coordinates. If NZVAR > M, you must input IJS and SIJ below to form M new coordinates. See DECOMP in $FORCE for the only circumstance in which you may enter a larger NZVAR without giving SIJ and IJS.

**** IZMAT defines simple internal coordinates ****

IZMAT is an array of integers defining each coordinate.

The general form for each internal coordinate is code number,I,J,K,L,M,N

IZMAT =1 followed by two atom numbers. (I-J bond length)

=2 followed by three numbers. (I-J-K bond angle)

=3followed by four numbers. (dihedral angle) Torsion angle between planes I-J-K and J-K-L.

=4followed by four atom numbers. (atom-plane) Out-of-plane angle from bond I-J to plane J-K-L.

=5followed by three numbers. (I-J-K linear bend) Counts as 2 coordinates for the degenerate bend, normally J is the center atom. See $LIBE.

=6followed by five atom numbers. (dihedral angle) Dihedral angle between planes I-J-K and K-L-M.

=7followed by six atom numbers. (ghost torsion) Let A be the midpoint between atoms I and J, and B be the midpoint between atoms M and N. This coordinate is the dihedral angle A-K-L-B. The atoms I,J and/or M,N may be the same atom number. (If I=J AND M=N, this is a conventional torsion). Examples: N2H4, or, with one common pair, H2POH.

Example - a nonlinear triatomic, atom 2 in the middle:

$ZMAT IZMAT(1)=1,1,2, 2,1,2,3, 1,2,3 $END

This sets up two bonds and the angle between them. The blanks between each coordinate definition are not necessary, but improve readability mightily.

**** the next define delocalized coordinates ****

DLCis a flag to request delocalized coordinates. (default is .FALSE.)

AUTOis a flag to generate all redundant coordinates, automatically. The DLC space will consist of all non-redundant combinations of these which can be found. The list of redundant coordinates will consist of bonds, angles, and torsions only. (default is .FALSE.)

NONVDWis an array of atom pairs which are to be joined by a bond, but might be skipped by the routine that automatically includes all distances shorter than the sum of van der Waals radii. Any angles and torsions associated with the new bond(s) are also automatically included.

The format for IXZMAT, IRZMAT, IFZMAT is that of IZMAT:

IXZMATis an extra array of simple internal coordinates which you want to have added to the list generated by AUTO. Unlike NONVDW, IXZMAT will add only the coordinate(s) you specify.

IRZMATis an array of simple internal coordinates which you would like to remove from the AUTO list of redundant coordinates. It is sometimes necessary to remove a torsion if other torsions around a bond are being frozen, to obtain a nonsingular G matrix.

IFZMATis an array of simple internal coordinates whichyou would like to freeze. See also FVALUE below. Note that IFZMAT/FVALUE work only with DLC, see the IFREEZ option in $STATPT to freeze coordinates if you wish to freeze simple or natural coordinates.

FVALUEis an array of values to which the internal coordinates should be constrained. It is not necessary to input $DATA such that the initial values match these desired final values, but it is helpful if the initial values are not too far away.

**** SIJ,IJS define natural internal coordinates ****

SIJis a transformation matrix of dimension NZVAR x M, used to transform the NZVAR internal coordinates in IZMAT into M new internal coordinates. SIJ is a sparse matrix, so only the non-zero elements are given, by using the IJS array described below. The columns of SIJ will be normalized by GAMESS. (Default: SIJ = I, unit matrix)

IJSis an array of pairs of indices, giving the row and column index of the entries in SIJ.

example - if the above triatomic is water, using

IJS(1) = 1,1, 3,1, 1,2, 3,2, 2,3

SIJ(1) = 1.0, 1.0, 1.0,-1.0, 1.0

gives the matrix S= 1.0 1.0 0.0

0.0 0.0 1.0

1.0 -1.0 0.0

which defines the symmetric stretch, asymmetric stretch, and bend of water.

references for natural internal coordinates:

P.Pulay, G.Fogarasi, F.Pang, J.E.Boggs J.Am.Chem.Soc. 101, 2550-2560(1979)

G.Fogarasi, X.Zhou, P.W.Taylor, P.Pulay J.Am.Chem.Soc. 114, 8191-8201(1992)

reference for delocalized coordinates:

J.Baker, A. Kessi, B.Delley J.Chem.Phys. 105, 192-212(1996)

$LIBE group (required if linear bends are used in $ZMAT)

A degenerate linear bend occurs in two orthogonal planes, which are specified with the help of a point A. The first bend occurs in a plane containing the atoms I,J,K and the user input point A. The second bend is in the plane perpendicular to this, and containing I,J,K. One such point must be given for each pair of bends used.

APTS(1)= x1,y1,z1,x2,y2,z2,... for linear bends 1,2,...

Note that each linear bend serves as two coordinates, so that if you enter 2 linear bends (HCCH, for example), the correct value of NZVAR is M-2, where M=3N-6 or 3N-5, as appropriate.

$SCF group relevant if SCFTYP = RHF, UHF, or ROHF,

required if SCFTYP = GVB)

This group of parameters provides additional control over the RHF, UHF, ROHF, or GVB SCF steps. It must be used for GVB open shell or perfect pairing wavefunctions.

DIRSCF =a flag to activate a direct SCF calculation, which is implemented for all the Hartree-Fock type wavefunctions: RHF, ROHF, UHF, and GVB. This keyword also selects direct MP2 computation. The default of .FALSE. stores integrals on disk storage for a conventional SCF calculation.

FDIFF =a flag to compute only the change in the Fock matrices since the previous iteration, rather than recomputing all two electron contributions. This saves much CPU time in the later iterations. This pertains only to direct SCF, and has a default of .TRUE. This option is implemented only for the RHF, ROHF, UHF cases.

Cases with many diffuse functions in the basis set sometimes oscillate at the end, rather than converging. Turning this parameter off will normally give convergence.

•The next flags affect convergence rates.

EXTRAP = controls Pople extrapolation of the Fock matrix.

DAMP = controls Davidson damping of the Fock matrix.

SHIFT = controls level shifting of the Fock matrix.

RSTRCT = controls restriction of orbital interchanges.

DIIS = controls Pulay's DIIS interpolation.

SOSCF =controls second order SCF orbital optimization.

(default=.TRUE. for RHF, Abelian group ROHF, GVB)

(default=.FALSE. for UHF, non-Abelian group ROHF)

DEM =controls direct energy minimization, which is implemented only for RHF. You must use a P supermatrix, $INTGRL NOPK=0. (default=.FALSE.)

defaults for EXTRAP DAMP SHIFT RSTRCT DIIS SOSCF

ab initio: T F F F T T/F

semiempirical: T F F F F F

The above parameters are implemented for all SCF wavefunction types, except that DIIS will work for GVB only for those cases with NPAIR=0 or NPAIR=1. If both DIIS and SOSCF are chosen, SOSCF is stronger than DIIS, and so DIIS will not be used.

Once either DIIS or SOSCF are initiated, any other accelerator in effect is put in abeyance.

•These parameters fine tune the various convergers.

NCONV = nSCF density convergence criteria. Convergence is reached when the density change between two consecutive SCF cycles is less than 10.0**(-n) in absolute value. One more cycle is executed after reaching convergence. Less accuracy in NCONV gives questionable gradients. (default is n=5, except CI or MP2 gradients n=6)

SOGTOL =second order gradient tolerance. SOSCF will be initiated when the orbital gradient falls below this threshold. (default=0.25 au)

ETHRSH =energy error threshold for initiating DIIS. The DIIS error is the largest element of e=FDS-SDF. Increasing ETHRSH forces DIIS on sooner. (default = 0.5 Hartree)

MAXDII =Maximum size of the DIIS linear equations, so that at most MAXDII-1 Fock matrices are used in the interpolation. (default=10)

DEMCUT =Direct energy minimization will not be done once the density matrix change falls below this threshold. (Default=0.5)

DMPCUT =Damping factor lower bound cutoff. The damping factor will not be allowed to drop below this value. (default=0.0)

note: The damping factor need not be zero to achieve valid convergence (see Hsu, Davidson, and Pitzer, J.Chem.Phys., 65, 609 (1976), see especially the section on convergence control), but it should not be astronomical either.

For more info on the convergence methods, see the 'Further Information' section.

•Miscellaneous options.

UHFNOS =flag controlling generation of the natural orbitals of a UHF function. (default=.FALSE.)

MVOQ = 0 Skip MVO generation (default)

= nForm modified virtual orbitals, using a cation with n electrons removed. Implemented for RHF, ROHF, and GVB. If necessary to reach a closed shell cation, the program might remove n+1 electrons. Typically, n will be about 6.

NPUNCH = SCF punch option

= 0 do not punch out the final orbitals

= 1 punch out the occupied orbitals

= 2 punch out occupied and virtual orbitals

The default is NPUNCH = 2.

•options for virial scaling

VTSCAL =A flag to request that the virial theorem be satisfied. An analysis of the total energy as an exact sum of orbital kinetic energies is printed. The default is .FALSE.

This option is implemented for RHF, UHF, and ROHF, for RUNTYP=ENERGY, OPTIMIZE, or SADPOINT. Related input is as follows:

SCALF =initial exponent scale factor when VTSCAL is in use, useful when restarting. The default is 1.0.

MAXVT =maximum number of iterations (at a single geometry) to satisfy the energy virial theorem. The default is 20.

VTCONV =convergence criterion for the VT, which is satisfied when 2<T> + <V> + R x dE/dR is less than VTCONV. The default is 1.0D-6 Hartree.

For more information on this option, which is most economically employed during a geometry search, see

M.Lehd and F.Jensen, J.Comput.Chem. 12, 1089-1096(1991).

•GVB/ROHF options

The next parameters define the GVB wavefunction. Note that ALPHA and BETA also have meaning for ROHF. See also MULT in the $CONTRL group. The GVB wavefunction assumes orbitals are in the order core, open, pairs.

NCO =The number of closed shell orbitals. The default almost certainly should be changed! (default=0).

NSETO =The number of sets of open shells in the function. Maximum of 10. (default=0)

NO =An array giving the degeneracy of each open shell set. Give NSETO values. (default=0,0,0,...).

NPAIR =The number of geminal pairs in the -GVB- function. Maximum of 12. The default corresponds to open shell SCF (default=0).

CICOEF =An array of ordered pairs of CI coefficients for the -GVB- pairs. For example, a two pair case for water, say, might be CICOEF(1)=0.95,0.05,0.95,-0.05. If not normalized, as in the default, they will be. This parameter is useful in restarting a GVB run, with the current CI coefficients. (default = 0.90,-0.20,0.90,-0.20,...)

COUPLE =A switch controlling the input of F, ALPHA, and BETA. The default is to use internally stored values for these variables. Note ALPHA and BETA can be given for -ROHF-, as well as -GVB-. (Default=.FALSE.)

F = An vector of fractional occupations.

ALPHA =An array of A coupling coefficients given in lower triangular order.

BETA = An array of B coupling coefficients given in lower triangular order.

Note: The default for F, ALPHA, and BETA depends on the state chosen. Defaults for the most commonly occurring cases are internally stored.

For more discussion of GVB/ROHF input see the 'further information' section

$SCFMI group (optional, relevant if SCFTYP=RHF)

The SCF-MI method is a modification of the Roothaan equations that avoids basis set superposition error (BSSE) in intermolecular interaction calculations, by expanding each monomer's orbitals using only its own basis set. Thus, the resulting orbitals are not orthogonal. The presence of a $SCFMI group in the input triggers the use of this option.

The implementation is limited to two monomers, treated at the RHF level. The energy, gradient, and therefore numerical hessian are available. The SCF step may be run in direct SCF mode. The first 4 parameters must be given. All atoms of monomer A must be given in $DATA before the atoms of monomer B.

NA = number of doubly occupied MOs on fragment A.

NB = number of doubly occupied MOs on fragment B.

MA = number of basis functions on fragment A.

MB = number of basis functions on fragment B.

ITER =maximum number of SCF-MI cycles, overriding the usual MAXIT value. (default is 50).

DTOL = SCF-MI density convergence criteria. (default is 1.0d-10)

ALPHA =possible level shift parameter. (default is 0.0, meaning shifting is not used)

IOPT = prints additional debug information.

= 0 standard outout (default)

= 1 print for each SCF-MI cycle MOs, overlap between the MOs, CPU times.

= 2 print some extra informations in secular systems solution.

MSHIFT =debugging option that permits to shift all the memory pointer of the SCFMI section of code of the quantity MSHIFT (default is 0).

"Modification of Roothan Equations to Exclude BSSE from Molecular Interaction Calculations"

E. Gianinetti, M. Raimondi, E. Tornaghi Int. J. Quantum Chem. 60, 157 (1996)

A. Famulari, E. Gianinetti, M. Raimondi, and M. Sironi Int. J. Quantum Chem. (1997), submitted.

$MP2 group (relevant to SCFTYP=RHF,UHF,ROHF if MPLEVL=2)

Controls 2nd order Moller-Plesset perturbation runs, if requested by MPLEVL in $CONTRL. See also the DIRSCF keyword in $SCF to select direct MP2. MP2 is implemented for RHF, high spin ROHF, or UHF wavefunctions. Analytic gradients and the first order correction to the wavefunction (i.e. properties) are available only for RHF. The $MP2 group is usually not given. See also $MCQDPT.

NCORE = nOmits the first n occupied orbitals from the calculation. The default for n is the number of chemical core orbitals.

MP2PRP =a flag to turn on property computation for RHF MP2 jobs with RUNTYP=ENERGY. This is appreciably more expensive than just evaluating the 2nd order energy correction alone, so the default is .FALSE. Properties are always computed during gradient runs, when they are an almost free byproduct.

LMOMP2 =a flag to turn on analysis of the MP2 energy in terms of localized orbitals. Any type of localized orbital may be used. This option is implemented only for RHF, and its selection forces use of the METHOD=3 transformation. The default is .FALSE.

The remaining parameters control execution characteristics

NWORD =controls memory usage. The default uses all available memory. (default=0)

CUTOFF = transformed integral retention threshold, the default is 1.0d-9.

METHOD = nselects transformation method, 2 being the segmented transformation, and 3 being a more conventional two phase bin sort implementation. 3 requires more disk, but less memory. The default is to attempt method 2 first, and method 3 second.

AOINTS = defines AO integral storage during conventional integral transformations, during parallel runs.

DUPstores duplicated AO lists on each node, and is the default for parallel computers with slow interprocessor communication, e.g. ethernet.

DISTdistributes the AO integral file across all nodes, and is the default for parallel computers with high speed communications.

$GUESS group (optional, relevant for all SCFTYP's)

This group controls the selection of initial molecular orbitals.

GUESS = Selects type of initial orbital guess.

= HUCKELCarry out an extended Huckel calculation using a Huzinaga MINI basis set, and project this onto the current basis. This is implemented for atoms up to Rn, and will work for any all electron or ECP basis set. (default for most runs)

= HCOREDiagonalize the one electron Hamiltonian to obtain the initial guess orbitals. This method is applicable to any basis set, but does not work as well as the HUCKEL guess.

= MOREADRead in formatted vectors punched by an earlier run. This requires a $VEC group, and you MUST pay attention to NORB below.

= MOSAVED(default for restarts) The initial orbitals are read from the DICTNRY file of the earlier run.

= SKIPBypass initial orbital selection. The initial orbitals and density matrix are assumed to be in the DICTNRY file.

All GUESS types except 'SKIP' permit reordering of the orbitals, carry out an orthonormalization of the orbitals, and generate the correct initial density matrix. The initial density matrix cannot be generated for -CI- and -MCSCF-, so property restarts for these wavefunctions will require 'SKIP' which is an otherwise seldom used option. Note that correct computation of a -GVB- density matrix requires CICOEF in $SCF. Another possible use for 'SKIP' is to speed up a EXETYP=CHECK job, or a RUNTYP=HESSIAN job where the hessian is supplied.

PRTMO = a flag to control printing of the initial guess. (default=.FALSE.)

NORB =The number of orbitals to be read in the $VEC group. This applies only to GUESS=MOREAD.

For -RHF-, -UHF-, -ROHF-, and -GVB-, NORB defaults to the number of occupied orbitals. NORB must be given for -CI- and -MCSCF-. For -UHF-, if NORB is not given, only the occupied alpha and beta orbitals should be given, back to back. Otherwise, both alpha and beta orbitals must consist of NORB vectors. NORB may be larger than the number of occupied MOs, if you wish to read in the virtual orbitals. If NORB is less than the number of atomic orbitals, the remaining orbitals are generated as the orthogonal complement to those read.

NORDER = Orbital reordering switch.

= 0 No reordering (default)

= 1 Reorder according to IORDER and JORDER.

IORDER = Reordering instructions.

Input to this array gives the new molecular orbital order. For example, IORDER(3)=4,3 will interchange orbitals 3 and 4, while leaving the other MOs in the original order. This parameter applies to all orbitals (alpha and beta) except for -UHF-, where it only affects the alpha MOs. (default is IORDER(i)=i )

JORDER = Reordering instructions.

Same as IORDER, but for the beta MOs of -UHF-.

TOLZ =level below which MO coefficients will be set to zero. (default=1.0E-7)

TOLE =level at which MO coefficients will be equated. This is a relative level, coefficients are set equal if one agrees in magnitude to TOLE times the other. (default=5.0E-5)

MIX =rotate the alpha and beta HOMO and LUMO orbitals so as to generate inequivalent alpha and beta orbital spaces. This pertains to UHF singlets only. (default=.FALSE.)

$VEC group (optional, relevant for all SCFTYP's)

(required if GUESS=MOREAD)

This group consists of formatted vectors, as written onto file PUNCH in a previous run. It is considered good form to retain the titling comment cards punched before the $VEC card, as labeling of what the $VEC is!

$STATPT group (optional, for RUNTYP=OPTIMIZE or SADPOINT)

This group controls the search for stationary points. Note that NZVAR in $CONTRL determines if the geometry search is conducted in Cartesian or internal coordinates.

METHOD = optimization algorithm selection. Pick from

NRStraight Newton-Raphson iterate. This will attempt to locate the nearest stationary point, which may be of any order. There is no steplength control. RUNTYP can be either OPTIMIZE or SADPOINT

RFORational Function Optimization. This is one of the augmented Hessian techniques where the shift parameter(s) is(are) chosen by a rational function approximation to the PES. For SADPOINT searches it involves two shift parameters. If the calculated stepsize is larger than DXMAX the step is simply scaled down to size.

QAQuadratic Approximation. This is another version of an augmented Hessian technique where the shift parameter is chosen such that the steplength is equal to DXMAX. It is completely equivalent to the TRIM method. (default)

SCHLEGEL The quasi-NR optimizer by Schlegel.

CONOPTCONstrained OPTimization. An algorithm which can be used for locating TSs. The starting geometry MUST be a minimum! The algorithm tries to push the geometry uphill along a chosen Hessian mode (IFOLOW) by a series of optimizations on hyperspheres of increasingly larger radii. Note that there currently are no restart capabilitites for this method, not even manually.

OPTTOL =gradient convergence tolerance, in Hartree/Bohr. Convergence of a geometry search requires the largest component of the gradient to be less than OPTTOL, and the root mean square gradient less than 1/3 of OPTTOL. (default=0.0001)

NSTEP =maximum number of steps to take. Restart data is punched if NSTEP is exceeded. (default=20)

•the next four control the step size

DXMAX =initial trust radius of the step, in Bohr.

For METHOD=RFO, QA, or SCHLEGEL, steps will be scaled down to this value, if necessary. (default=0.3 for OPTIMIZE and 0.2 for SADPOINT)

For METHOD=NR, DXMAX is inoperative.

For METHOD=CONOPT, DXMAX is the step along the previous two points to increment the hypersphere radius between constrained optimizations. (default=0.1)

•the next three apply only to METHOD=RFO or QA:

TRUPD =a flag to allow the trust radius to change as the geometry search proceeds. (default=.TRUE.)

TRMAX =maximum permissible value of the trust radius.

(default=0.5 for OPTIMIZE and 0.3 for SADPOINT)

TRMIN =minimum permissible value of the trust radius. (default=0.05)

•the next three control mode following

IFOLOW = Mode selection switch, for RUNTYP=SADPOINT.

For METHOD=RFO or QA, the mode along which the energy is maximized, other modes are minimized. Usually refered to as "eigenvector following".

For METHOD=SCHLEGEL, the mode whose eigenvalue is (or will be made) negative. All other curvatures will be made positive.

For METHOD=CONOPT, the mode along which the geometry is initially perturbed from the minima. (default is 1)

In Cartesian coordinates, this variable doesn't count the six translation and rotation degrees. Note that the "modes" aren't from mass-weighting.

STPT =flag to indicate whether the initial geometry is considered a stationary point. If .true. the initial geometry will be perturbed by a step along the IFOLOW normal mode with stepsize STSTEP. (default=.false.) The positive direction is taken as the one where the largest component of the Hessian mode is positive. If there are more than one largest component (symmetry), the first is taken as positive.

Note that STPT=.TRUE. has little meaning with HESS=GUESS as there will be many degenerate eigenvalues.

STSTEP =Stepsize for jumping off a stationary point. (default=0.01)

IFREEZ =array of internal coordinates to freeze. For example, IFREEZ(1)=1,3 freezes the two bond lengths in the $ZMAT example, while optimizing the angle. You cannot freeze Cartesian coords.

•The next two control the hessian matrix quality

HESS = selects the initial hessian matrix.

= GUESSchooses a positive definite diagonal hessian. (default for RUNTYP=OPTIMIZE)

= READcauses the hessian to be read from a $HESS group. (default for RUNTYP=SADPOINT)

= RDABreads only the ab initio part of the hessian, and approximates the effective fragment blocks.

= RDALLreads the full hessian, then converts any fragment blocks to 6x6 T+R shape. (this option is seldom used).

= CALCcauses the hessian to be computed, see the $FORCE group.

IHREP =the number of steps before the hessian is recomputed. If given as 0, the hessian will be computed only at the initial geometry if you choose HESS=CALC, and never again. If nonzero, the hessian is recalculated every IHREP steps, with the update formula used on other steps. (default=0)

•the next two control the amount of output

Let 0 mean the initial geometry, L mean the last geometry, and all mean every geometry. Let INTR mean the internuclear distance matrix. Let HESS mean the approximation to the hessian. Note that a directly calculated hessian matrix will always be punched, NPUN refers only to the updated hessians used by the quasi-Newton step.

NPRT = 1 Print INTR at all, orbitals at all

0 Print INTR at all, orbitals at 0+L (default)

-1 Print INTR at all, orbitals never

-2 Print INTR at 0+L, orbitals never

NPUN = 3 Punch all orbitals and HESS at all

2 Punch all orbitals at all

1 same as 0, plus punch HESS at all

0Punch all orbitals at 0+L, otherwise only occupied orbitals (default)

-1 Punch occ orbitals at 0+L only

-2 Never punch orbitals

HSSEND =a flag to control automatic hessian evaluation at the end of a successful geometry search. (default=.FALSE.)

MOVIE =a flag to create a series of structural data which can be show as a movie by the Macintosh program Chem3D. The data is written to the file IRCDATA. (default=.FALSE.)

---- the following parameters are quite specialized ----

PURIFY =a flag to help eliminate the rotational and translational degrees of freedom from the initial hessian (and possibly initial gradient). This is much like the variable of the same name in $FORCE, and will be relevant only if internal coordinates are in use. (default=.FALSE.)

PROJCT =a flag to eliminate translation and rotational degrees of freedom from Cartesian optimizations. The default is .TRUE. since this normally will reduce the number of steps, except that this variable is set false when POSITION=FIXED is used during EFP runs.

ITBMAT =number of micro-iterations used to compute the step in Cartesians which corresponds to the desired step in internals. The default is 5.

UPHESS = SKIP do not update Hessian (not recommended)

BFGS default for OPTIMIZE using RFO or QA

POWELL default for OPTIMIZE using NR or CONOPT

POWELL default for SADPOINT

MSP mixed Murtagh-Sargent/Powell update

SCHLEGEL only choice for METHOD=SCHLEGEL

RESTAR =Enables restart of an optimization run. This can only be used with IREST .ne. 0 in $CONTRL. Use of this variable is discouraged.

---- NNEG, RMIN, RMAX, RLIM apply only to SCHLEGEL ----

NNEG =The number of negative eigenvalues the force constant matrix should have. If necessary the smallest eigenvalues will be reversed. The default is 0 for RUNTYP=OPTIMIZE, and 1 for RUNTYP=SADPOINT.

RMIN =Minimum distance threshold. Points whose root mean square distance from the current point is less than RMIN are discarded. (default=0.0015)

RMAX =Maximum distance threshold. Points whose root mean square distance from the current point is greater than RMAX are discarded. (default=0.1)

RLIM =Linear dependence threshold. Vectors from the current point to the previous points must not be collinear. (default=0.07)

•See the 'further information' section for some help with OPTIMIZE and SADPOINT runs

$TRUDGE group (optional, required for RUNTYP=TRUDGE)

This group defines the parameters for a non-gradient optimization of exponents or the geometry. The TRUDGE package is a modified version of the same code from Michel Dupuis' HONDO 7.0 system, originally written by H.F.King. Presently the program allows for the optimization of 10 parameters.

Exponent optimization works only for uncontracted primitives, without enforcing any constraints. Two non-symmetry equivalent H atoms would have their p function exponents optimized separately, and so would two symmetry equivalent atoms! A clear case of GIGO.

Geometry optimization works only in HINT internal coordinates (see $CONTRL and $DATA groups). The total energy of all types of SCF wavefunctions can be optimized, although this would be extremely stupid as gradient methods are far more efficient. The main utility is for open shell MP2 or CI geometry optimizations, which may not be done in any other way with GAMESS.

OPTMIZ =a flag to select optimization of either geometry or exponents of primitive gaussian functions.

= BASIS for basis set optimization.

= GEOMETRYfor geometry optimization (default). This means minima search only, there is no saddle point capability.

NPAR = number of parameters to be optimized.

IEX = defines the parameters to be optimized.

If OPTMIZ=BASIS, IEX declares the serial number of the Gaussian primitives for which the exponents will be optimized.

If OPTMIZ=GEOMETRY, IEX define the pointers to the HINT internal coordinates which will be optimized. (Note that not all internal coordinates have to be optimized.) The pointers to the internal coordinates are defined as: (the number of atom on the input list)*10 + (the number of internal coordinate for that atom). For each atom, the HINT internal coordinates are numbered as 1, 2, and 3 for BOND, ALPHA, and BETA, respectively.

P =Defines the initial values of the parameters to be optimized. You can use this to reset values given in $DATA. If omitted, the $DATA values are used. If given here, geometric data must be in Angstroms and degrees.

A complete example is a TCSCF multireference 6-31G geometry optimization for methylene,

$CONTRL SCFTYP=GVB CITYP=GUGA RUNTYP=TRUDGE

COORD=HINT $END

$BASIS GBASIS=N31 NGAUSS=6 $END

$DATA

Methylene TCSCF+CISD geometry optimization

Cnv 2

C 6. LC 0.00 0.0 0.00 - O K

H 1. PCC 1.00 53. 0.00 + O K I

$END

$SCF NCO=3 NPAIR=1 $END

$TRUDGE OPTMIZ=GEOMETRY NPAR=2

IEX(1)=21,22 P(1)=1.08 $END

$CIDRT GROUP=C2V SOCI=.TRUE. NFZC=1 NDOC=3 NVAL=1

NEXT=-1 $END

using GVB-PP(1), or TCSCF orbitals in the CI. The starting bond length is reset to 1.09, while the initial angle will be 106 (twice 53). Result after 17 steps is R=1.1283056, half-angle=51.83377, with a CI energy of -38.9407538472

Note that you may optimize the geometry for an excited CI state, just specify

$GUGDIA NSTATE=5 $END

$GUGDM IROOT=3 $END

to find the equilibrium geometry of the third state (of five total states) of the symmetry implied by your $CIDRT.

$TRURST group (optional, relevant for RUNTYP=TRUDGE)

This group specifies restart parameters for TRUDGE runs and accuracy thresholds.

KSTARTindicates the conjugate gradient direction in which the optimization will proceed. ( default = -1 )

-1 .... indicates that this is a non-restart run.

0 .... corresponds to a restart run.

FNOISEaccuracy of function values. Variation smaller than FNOISE are not considered to be significant (Def. 0.0005)

TOLF accuracy required of the function (Def. 0.001)

TOLR accuracy required of conjugate directions (Def. 0.05)

For geometry optimization, the values which give better results (closer to the ones obtained with gradient methods) are: TOLF=0.0001, TOLR=0.001, FNOISE=0.00001

$FORCE group

(optional, relevant for RUNTYP=HESSIAN,OPTIMIZE,SADPOINT)

This group controls the computation of the hessian matrix (the energy second derivative tensor, also known as the force constant matrix), and an optional harmonic vibrational analysis. This can be a very time consuming calculation. However, given the force constant matrix, the vibrational analysis for an isotopically substituted molecule is very cheap. Related input is HESS= in $STATPT, and the $MASS, $HESS, $GRAD, $DIPDR, $VIB groups.

METHOD = chooses the computational method.

= ANALYTICis implemented only for SCFTYPs RHF, ROHF, and GVB (when NPAIR is 0 or 1). This is the default for these cases.

= NUMERICis the default for all other cases: UHF, MCSCF, and all MP2 or CI runs.

RDHESS =a flag to read the hessian from a $HESS group, rather than computing it. This variable pertains only to RUNTYP=HESSIAN. See also HESS= in the $STATPT group. (default is .FALSE.)

PURIFY =controls cleanup

Given a $ZMAT, the hessian and dipole derivative tensor can be "purified" by transforming from Cartesians to internals and back to Cartesians. This effectively zeros the frequencies of the translation and rotation "modes", along with their IR intensities. The purified quantities are punched out. Purification does change the Hessian slightly, frequencies at a stationary point can change by a wave number or so. The change is bigger at nonstationary points. (default=.FALSE. if $ZMAT is given)

PRTIFC =prints the internal coordinate force constants. You MUST have defined a $ZMAT group to use this. (Default=.FALSE.)

--- the next four apply only to METHOD=NUMERIC ----

NVIB =Number of displacements in each Cartesian direction for force field computation.

= 1Move one VIBSIZ unit in each positive Cartesian direction. This requires 3N+1 evaluations of the wavefunction, energy, and gradient, where N is the number of SYMMETRY UNIQUE atoms given in $DATA. (default)

= 2Move one VIBSIZ unit in the positive direction and one VIBSIZ unit in the negative direction. This requires 6N+1 evaluations of the wavefunction and gradient, and gives a small improvement in accuracy. In particular, the frequencies will change from NVIB=1 results by no more than 10-100 wavenumbers, and usually much less. However, the normal modes will be more nearly symmetry adapted, and the residual rotational and translational "frequencies" will be much closer to zero.

VIBSIZ = Displacement size (in Bohrs). Default=0.01

Let 0 mean the Vib0 geometry, and D mean all the displaced geometries

NPRT = 1 Print orbitals at 0 and D

= 0 Print orbitals at 0 only (default)

NPUN = 2 Punch all orbitals at 0 and D

= 1 Punch all orbitals at 0 and occupied orbs at D

= 0 Punch all orbitals at 0 only (default)

----- the rest control normal coordinate analysis ----

VIBANL = flag to activate vibrational analysis.

(the default is .TRUE. for RUNTYP=HESSIAN, and otherwise is .FALSE.)

SCLFAC =scale factor for vibrational frequencies, used in calculating the zero point vibrational energy. Some workers correct for the usual overestimate in SCF frequencies by a factor 0.89. The output always prints unscaled frequencies, this value is used only in the thermochemical analysis. (Default is 1.0)

TEMP =an array of up to ten temperatures at which the thermochemistry should be printed out. The default is a single temperature, 298.15 K. To use absolute zero, input 0.001 degrees.

FREQ =an array of vibrational frequencies. If the frequencies are given here, the hessian matrix is not computed or read. You enter any imaginary frequencies as negative numbers, omit the zero frequencies corresponding to translation and rotation, and enter all true vibrational frequencies. Thermodynamic properties will be printed, nothing else is done by the run.

PRTSCN =flag to print contribution of each vibrational mode to the entropy. (Default is .FALSE.)

DECOMP =activates internal coordinate analysis. Vibrational frequencies will be decomposed into "intrinsic frequencies", by the method of J.A.Boatz and M.S.Gordon, J.Phys.Chem., 93, 1819-1826(1989). If set .TRUE., the $ZMAT group may define more than 3N-6 (3N-5) coordinates. (default=.FALSE.)

PROJCT = controls the projection of the hessian matrix.

The projection technique is described by W.H.Miller, N.C.Handy, J.E.Adams in J. Chem. Phys. 1980, 72, 99-112. At stationary points, the projection simply eliminates rotational and translational contaminants. At points with non-zero gradients, the projection also ensures that one of the vibrational modes will point along the gradient, so that there are a total of 7 zero frequencies. The other 3N-7 modes are constrained to be orthogonal to the gradient. Because the projection has such a large effect on the hessian, the hessian punched is the one BEFORE projection. For the same reason, the default is .FALSE. to skip the projection, which is mainly of interest in dynamical calculations.

There is a set of programs for the calculation of kinetic or equilibrium isotope effects from the group of Piotr Paneth at the University of Lodz. This ISOEFF package will accept data computed by GAMESS, and can be downloaded at http://ck-sg.p.lodz.pl/isoeff/isoeff.html

This group controls the solution of the response equations, also known as coupled Hartree-Fock.

POLAR =a flag to request computation of the static polarizability, alpha. Because this property needs 3 additional response vectors, beyond those needed for the hessian, the default is to skip the property. (default = .FALSE.)

NWORD =controls memory usage for this step. The default uses all available memory. (default=0)

(relevant for RUNTYP=IRC if FREQ,CMODE not given)

(relevant for RUNTYP=OPTIMIZE,SADPOINT if HESS=READ)

Formatted force constant matrix (FCM), i.e. hessian matrix. This data is punched out by a RUNTYP=HESSIAN job, in the correct format for subsequent runs. The first card in the group must be a title card.

A $HESS group is always punched in Cartesians. It will be transformed into internal coordinate space if a geometry search uses internals. It will be mass weighted (according to $MASS) for IRC and frequency runs.

The initial FCM is updated during the course of a geometry optimization or saddle point search, and will be punched if a run exhausts its time limit. This allows restarts where the job leaves off. You may want to read this FCM back into the program for your restart, or you may prefer to regenerate a new initial hessian. In any case, this updated hessian is absolutely not suitable for frequency prediction!

$GRAD group (relevant for RUNTYP=OPTIMIZE or SADPOINT)

(relevant for RUNTYP=HESSIAN when RDHESS=.TRUE.)

Formatted gradient vector at the $DATA geometry. This data is read in the same format it was punched out.

For RUNTYP=HESSIAN, this information is used to determine if you are at a stationary point, and possibly for projection. If omitted, the program pretends the gradient is zero, and otherwise proceeds normally.

For geometry searches, this information (if known) can be read into the program so that the first step can be taken instantly.

$DIPDR group (relevant for RUNTYP=HESSIAN if RDHESS=.T.)

Formatted dipole derivative tensor, punched in a previous RUNTYP=HESSIAN job. If this group is omitted, then a vibrational analysis will be unable to predict the IR intensities, but the run can otherwise proceed.

$VIB group (relevant for RUNTYP=HESSIAN, METHOD=NUMERIC)

Formatted card image -restart- data. This data is read in the format it was punched by a previous HESSIAN job to the file IRCDATA. Just add a " $END" card, and if the final gradient was punched as zero, delete the last set of data. Normally, IREST in $CONTRL will NOT be used in conjunction with a HESSIAN restart. The mere presence of this deck triggers the restart from cards. This deck can also be used to turn a single point differencing run into double differencing, as well as recovering from time limits, or other bombouts.

$MASS group (relevant for RUNTYP=HESSIAN, IRC, or DRC)

This group permits isotopic substitution during the computation of mass weighted Cartesian coordinates. Of course, the masses affect the frequencies and normal modes of vibration.

AMASS =An array giving the atomic masses, in amu. The default is to use the mass of the most abundant isotope. Masses through element 104 are stored.

example - $MASS AMASS(3)=2.0140 $END

will make the third atom in the molecule a deuterium.

$IRC group (relevant for RUNTYP=IRC)

This group governs the location of the intrinsic reaction coordinate, a steepest descent path in mass weighted coordinates, that connects the saddle point to reactants and products.

----- there are five integration methods chosen by PACE.

PACE = GS2selects the Gonzalez-Schlegel second order method. This is the default method.

Related input is:

GCUTcutoff for the norm of the mass-weighted gradient tangent (the default is chosen in the range from 0.00005 to 0.00020, depending on the value for STRIDE chosen below.

RCUTcutoff for Cartesian RMS displacement vector. (the default is chosen in the range 0.0005 to 0.0020 Bohr, depending on the value for STRIDE)

ACUTmaximum angle from end points for linear interpolation (default=5 degrees)

MXOPTmaximum number of constrained optimization steps for each IRC point (default=20)

IHUPDis the hessian update formula. 1 means Powell, 2 means BFGS (default=2)

GA is a gradient from the previous IRC point, and is used when restarting.

OPTTOLis a gradient cutoff used to determine if the IRC is approaching a minimum. It has the same meaning as the variable in $STATPT. (default=0.0001)

PACE = LINEAR selects linear gradient following (Euler's method).

Related input is:

STABLZswitches on Ishida/Morokuma/Komornicki reaction path stabilization. The default is .TRUE.

DELTAinitial step size along the unit bisector, if STABLZ is on. Default=0.025 Bohr.

ELBOWis the collinearity threshold above which the stabilization is skipped. If the mass weighted gradients at QB and QC are almost collinear, the reaction path is deemed to be curving very little, and stabilization isn't needed. The default is 175.0 degrees. To always perform stabilization, input 180.0.

READQB,EB,GBNORM,GB are energy and gradient data

already known at the current IRC point. If it happens that a run with STABLZ on decides to skip stabilization because of ELBOW, this data will be punched to speed the restart.

PACE = QUAD selects quadratic gradient following.

Related input is:

SAB distance to previous point on the IRC.

GA gradient vector at that historical point.

PACE = AMPC4selects the fourth order Adams-Moulton variable step predictor-corrector.

Related input is:

GA0,GA1,GA2 which are gradients at previous points.

PACE = RK4selects the 4th order Runge-Kutta variable step method. There is no related input.

----- The next two are used by all PACE choices -----

STRIDE =Determines how far apart points on the reaction path will be. STRIDE is used to calculate the step taken, according to the PACE you choose. The default is good for the GS2 method, which is very robust. Other methods should request much smaller step sizes, such as 0.10 or even 0.05. (default = 0.30 sqrt(amu)-Bohr)

NPOINT =The number of IRC points to be located in this run. The default is to find only the next point. (default = 1)

----- The next two let you choose your output volume -----

Let F mean the first IRC point found in this run, and L mean the final IRC point of this run. Let INTR mean the internuclear distance matrix.

NPRT = 1 Print INTR at all, orbitals at all IRC points

0 Print INTR at all, orbitals at F+L (default)

-1 Print INTR at all, orbitals never

-2 Print INTR at F+L, orbitals never

NPUN = 1 Punch all orbitals at all IRC points

0Punch all orbitals at F+L, only occupied orbitals at IRC points between (default)

-1 Punch all orbitals at F+L only

-2 Never punch orbitals

• The next two tally the reaction path results. The defaults are appropriate for starting from a saddle point, restart values are automatically punched out.

NEXTPT = The number of the next point to be computed.

STOTAL =Total distance along the reaction path to next IRC point, in mass weighted Cartesian space.

• The following controls jumping off the saddle point. If you give a $HESS group, FREQ and CMODE will be generated automatically.

SADDLE =A logical variable telling if the coordinates given in the $DATA deck are at a saddle point (.TRUE.) or some other point lying on the IRC (.FALSE.). If SADDLE is true, either a $HESS group or else FREQ and CMODE must be given. (default = .FALSE.)

Related input is:

TSENGY =A logical variable controlling whether the energy and wavefunction are evaluated at the transition state coordinates given in $DATA. Since you already know the energy from the transition state search and force field runs, the default is .F.

FORWRD =A logical variable controlling the direction to proceed away from a saddle point. The forward direction is defined as the direction in which the largest magnitude component of the imaginary normal mode is positive. (default =.TRUE.)

EVIB =Desired decrease in energy when following the imaginary normal mode away from a saddle point. (default=0.0005 Hartree)

FREQ = The magnitude of the imaginary frequency, given in cm**-1.

CMODE =An array of the components of the normal mode whose frequency is imaginary, in Cartesian coordinates. Be careful with the signs!

You must give FREQ and CMODE if you don't give a $HESS group, when SADDLE=.TRUE. The option of giving these two variables instead of a $HESS does not apply to the GS2 method, which must have a hessian input, even for restarts. Note also that EVIB is ignored by GS2 runs.

•For hints about IRC tracking, see the 'further information' section.

$GRADEX group (optional, for RUNTYP=GRADEXTR)

This group controls the gradient extremal following algorithm. The GEs leave stationary points parallel to each of the normal modes of the hessian. Sometimes a GE leaving a minimum will find a transition state, and thus provides us with a way of finding that saddle point. GEs have many unusual mathematical properties, and you should be aware that they normally differ a great deal from IRCs.

The search will always be performed in cartesian coordinates, but internal coordinates along the way may be printed by the usual specification of NZVAR and $ZMAT.

METHOD = algorithm selection.

SRA predictor-corrector method due to Sun and Ruedenberg (default).

JJH A method due to Jorgensen, Jensen and Helgaker.

NSTEP = maximum number of predictor steps to take. (default=50)

DPRED = the stepsize for the predictor step. (default = 0.10)

STPT =a flag to indicate whether the initial geometry is considered a stationary point. If .TRUE., the geometry will be perturbed by STSTEP along the IFOLOW normal mode. (default = .TRUE.)

STSTEP =the stepsize for jumping away from a stationary point. (default = 0.01)

IFOLOW = Mode selection option. (default is 1)

If STPT=.TRUE., the initial geometry will be perturbed by STSTEP along the IFOLOW normal mode. Note that IFOLOW can be positive or negative, depending on the direction the normal mode should be followed in. The positive direction is defined as the one where the largest component of the Hessian eigenvector is positive.

If STPT=.FALSE. the sign of IFOLOW determines which direction the GE is followed in. A positive value will follow the GE in the uphill direction. The value of IFOLOW should be set to the Hessian mode which is parallel to the gradient to avoid miscellaneous warning messages.

GOFRST =a flag to indicate whether the algorithm should attempt to locate a stationary point. If .TRUE., a straight NR search is performed once the NR step length drops below SNRMAX. 10 NR step are then allowed, a value which cannot be changed. (default = .TRUE.)

SNRMAX =upper limit for switching to straight NR search for stationary point location. (default = 0.10 or DPRED, whichever is smallest)

OPTTOL =gradient convergence tolerance, in Hartree/Bohr. Used for optimizing to a stationary point. Convergence of a geometry search requires the rms gradient to be less than OPTTOL. (default=0.0001)

HESS =selection of the initial hessian matrix, if STPT=.TRUE.

= READ causes the hessian to be read from a $HESS group.

= CALC causes the hessian to be computed. (Default)

•The rest of the parameters apply only to METHOD=SR

DELCOR =the corrector step should be smaller than this value before the next predictor step is taken. (default = 0.001)

MYSTEP =maximum number of micro iteration allowed to bring the corrector step length below DELCOR. (default=20)

SNUMH =stepsize used in the numerical differentiation of the Hessian to produce third derivatives. (default = 0.0001)

HSDFDB =flag to select determination of third derivatives. At the current geometry we need the gradient, the Hessian, and the partial third derivative matrix in the gradient direction.

If .TRUE., the gradient is calculated at the current geometry, and two Hessians are calculated at SNUMH distance to each side in the gradient direction. The Hessian at the geometry is formed as the average of the two displaced Hessians.

If .FALSE., both the gradient and Hessian are calculated at the current geometry, and one additional Hessian is calculated at SNUMH in the gradient direction.

The default double-sided differentiation produces a more accurate third derivative matrix, at the cost of an additional wave function and gradient. (default = .TRUE.)

See the 'further information' section for some help with GRADEXTR runs.

$DRC group (relevant for RUNTYP=DRC)

This group governs the dynamical reaction coordinate, a classical trajectory method based on quantum chemical potential energy surfaces. In GAMESS these may be either ab initio or semi-empirical. Because the vibrational period of a normal mode with frequency 500 wavenumbers is 67 fs, a DRC needs to run for many steps in order to sample a representative portion of phase space. Almost all DRCs break molecular symmetry, so build your molecule with C1 symmetry in $DATA, or specify NOSYM=1 in $CONTRL. Restart data can be found in the job's OUTPUT file, with important results summarized to the IRCDATA file.

NSTEP =The number of DRC points to be calculated, not including the initial point. (default = 1000)

DELTAT = is the time step. (default = 0.1 fs)

TOTIME =total duration of the DRC computed in a previous job, in fs. The default is the correct value when initiating a DRC. (default=0.0 fs)

In general, a DRC can be initiated anywhere, so $DATA might contain coordinates of the equilibrium geometry, or a nearby transition state, or something else. You must also supply an initial kinetic energy, and the direction of the initial velocity, for which there are a number of options:

EKIN =The initial kinetic energy (default = 0.0 kcal/mol) See also ENM, NVEL, and VIBLVL regarding alternate ways to specify the initial value.

VEL =an array of velocity components, in Bohr/fs. When NVEL is false, this is simply the direction of the velocity vector. Its magnitude will be automatically adjusted to match the desired initial kinetic energy, and it will be projected so that the translation of the center of mass is removed. Give in the order vx1, vy1, vz1, vx2, vy2, ...

NVEL =a flag to compute the initial kinetic energy from the input VEL using the sum of mass*VEL*VEL/2. This flag is usually selected only for restarts. (default=.FALSE.)

The next two allow the kinetic energy to be partitioned over all normal modes. The coordinates in $DATA are likely to be from a stationary point! You must also supply a $HESS group.

VIBLVL = a flag to turn this option on (default=.FALSE.)

VIBENG =an array of energies (in units of multiples of the hv of each mode) to be imparted along each normal mode. The default is to assign the zero point energy only, VIBENG(1)=0.5, 0.5, ..., 0.5. If given as a negative number, the initial direction of the velocity vector is along the reverse direction of the mode. "Reverse" means the phase of the normal mode is chosen such that the largest magnitude component is a negative value. An example might be VIBENG(4)=2.5 to add two quanta to mode 4, along with zero point energy in all modes.

The next three pertain to initiating the DRC along a single normal mode of vibration. No kinetic energy is assigned to the other modes. You must also supply a $HESS group.

NNM =The number of the normal mode to which the initial kinetic energy is given. The absolute value of NNM must be in the range 1, 2, ..., 3N-6. If NNM is a positive/negative value, the initial velocity will lie in the forward/reverse direction of the mode. "Forward" means the largest component of the normal mode is a positive value. (default=0)

ENM =the initial kinetic energy given to mode NNM, in units of vibrational quanta hv, so the amount depends on mode NNM's vibrational frequency, v. If you prefer to impart an arbitrary initial kinetic energy to mode NNM, specify EKIN instead. (default = 0.0 quanta)

To summarize, there are five different ways to specify the DRC trajectory:

1.VEL vector with NVEL=.TRUE. This is difficult to specify at your initial point, and so this option is mainly used when restarting your trajectory. The restart information is always in this format.

2.VEL vector and EKIN with NVEL=.FALSE. This will give a desired amount of kinetic energy in the direction of the velocity vector.

3.VIBLVL and VIBENG selected, to give initial kinetic energy to all of the normal modes.

4. NNM and ENM to give quanta to a single normal mode.

5.NNM and EKIN to give arbitrary kinetic energy to a single normal mode.

The most common use of the next two is to analyze a trajectory with respect to the minimum energy geometry the trajectory is traveling around.

NMANAL =a flag to select mapping of the mass-weighted Cartesian DRC coordinates and velocity (conjugate momentum) in terms of normal modes step by step. If you choose this option, you must supply both C0 and a $HESS group from the stationary point. (default=.FALSE.)

C0 =an array of the coordinates of the stationary point (the coordinates in $DATA might well be some other coordinates). Give in the order x1,y1,z1,x2,y2,...

The next option applies to all input paths which read a hessian: NMANAL, NNM, or VIBLVL. After the translations and rotations have been dropped, the normal modes are renumbered 1, 2, ..., 3N-6.

HESSTS =a flag to say if the hessian corresponds to a transition state or a minimum. This parameter controls deletion of the translation and rotation degrees of freedom, i.e. the default is to drop the first six "modes", while setting this flag on drops modes 2 to 7 instead. (default=.FALSE.)

The final variables control the volume of output. Let F mean the first DRC point found in this run, and L mean the last DRC point of this run.

NPRTSM =summarize the DRC results every NPRTSM steps, to the file IRCDATA. (default = 1)

NPRT = 1 Print orbitals at all DRC points

0 Print orbitals at F+L (default)

-1 Never print orbitals

NPUN = 2 Punch all orbitals at all DRC points

1Punch all orbitals at F+L, and occupied orbitals at DRC points between

0 Punch all orbitals at F+L only (default)

-1 Never punch orbitals

References:

J.J.P.Stewart, L.P.Davis, L.W.Burggraf, J.Comput.Chem. 8, 1117-1123 (1987)

S.A.Maluendes, M.Dupuis, J.Chem.Phys. 93, 5902-5911 (1990)

T.Taketsugu, M.S.Gordon, J.Phys.Chem. 99, 8462-8471 (1995)

T.Taketsugu, M.S.Gordon, J.Phys.Chem. 99, 14597-604 (1995)

T.Taketsugu, M.S.Gordon, J.Chem.Phys. 103, 10042-9(1995)

T.Taketsugu, M.S.Gordon, J.Chem.Phys. 104, 2834-40(1996)

M.S.Gordon, G.Chaban, T.Taketsugu J.Phys.Chem. 100, 11512-11525(1996)

$SURF group (relevant for RUNTYP=SURFACE)

This group allows you to probe a potential energy surface along a small grid of points. Note that there is no option to vary angles, only distances. The scan can be made for any SCFTYP, or for the MP2 or CI surface.

IVEC1 =an array of two atoms, defining a coordinate from the first atom given to the second.

IGRP1 =an array specifying a group of atoms, which must include the second atom given in IVEC1. The entire group will be translated (rigidly) along the vector IVEC1, relative to the first atom given in IVEC1.

ORIG1 =starting value of the coordinate, which may be positive or negative. Zero corresponds to the distance given in $DATA.

DISP1 =step size for the coordinate.

NDISP1 =number of steps to take for this coordinate.

There are no reasonable defaults for these keywords, so you should input all of them. ORIG1 and DISP1 should be given in Angstrom.

IVEC2, IGRP2, ORIG2, DISP2, NDISP2 = have the identical meaning as their "1" counterparts, and permit you to make a two dimensional map along two displacement coordinates. If the "2" data are not input, the surface map proceeds in only one dimension.

Note that properties are not computed at these points, other than the energy.

$LOCAL group (relevant for LOCAL=RUEDNBRG, BOYS, or POP)

This group allows input of additional data to control the localization methods. If no input is provided, the valence orbitals will be localized as much as possible, while still leaving the wavefunction invariant.

PRTLOC =a flag to control supplemental printout. The extra output is the rotation matrix to the localized orbitals, and, for the Boys method, the orbital centroids, for the Ruedenberg method, the coulomb and exchange matrices, for the population method, atomic populations. (default=.FALSE.)

MAXLOC =maximum number of localization cycles. This applies to BOYS or POP methods only. If the localization fails to converge, a different order of 2x2 pairwise rotations will be tried. (default=250)

CVGLOC =convergence criterion. The default provides LMO coefficients accurate to 6 figures. (default=1.0E-6)

SYMLOC =a flag to restrict localization so that orbitals of different symmetry types are not mixed. This option is not supported in all possible point groups. The purpose of this option is to give a better choice for the starting orbitals for GVB-PP or MCSCF runs, without destroying the orbital's symmetry. This option is compatible with each of the 3 methods of selecting the orbitals to be included. (default=.FALSE.)

These parameters select the orbitals which are to be included in the localization. You may select from FCORE, NOUTA/NOUTB, or NINA/NINB, but may choose only one of these.

FCORE =flag to freeze all the chemical core orbitals present. All the valence orbitals will be localized. (default=.TRUE.)

NOUTA =number of alpha orbitals to hold fixed in the localization. (default=0)

MOOUTA =an array of NOUTA elements giving the numbers of the orbitals to hold fixed. For example, the input NOUTA=2 MOOUTA(1)=8,13 will freeze only orbitals 8 and 13. You must enter all the orbitals you want to freeze, including any cores. This variable has nothing to do with cows.

NOUTB =number of beta orbitals to hold fixed in -UHF- localizations. (default=0)

MOOUTB =same as MOOUTA, except that it applies to the beta orbitals, in -UHF- wavefunctions only.

NINA =number of alpha orbitals which are to be included in the localization. (default=0)

MOINA =an array of NINA elements giving the numbers of the orbitals to be included in the localization. Any orbitals not mentioned will be frozen.

NINB =number of -UHF- beta MOs in the localization. (default=0)

MOINB =same as MOINA, except that it applies to the beta orbitals, in -UHF- wavefunctions only.

N.B. Since Boys localization needs the dipole integrals, do not turn off dipole moment calculation in $ELMOM.

•The following keywords are used for the localized charge distribution (LCD) energy decomposition.

EDCOMP =flag to turn on LCD energy decomposition. Note that this method is currently implemented for SCFTYP=RHF and ROHF and LOCAL=RUEDNBRG only. The SCF LCD forces all orbitals to be localized, overriding input on the previous page. See also LMOMP2 in the $MP2 group. (default = .FALSE.)

MOIDON =flag to turn on LMO identification and subsequent LMO reordering, and assign nuclear LCD automatically. (default = .FALSE.)

DIPDCM =flag for LCD molecular dipole decomposition. (default = .FALSE.)

QADDCM = flag for LCD molecular quadrupole decomposition. (default = .FALSE.)

POLDCM =flag to turn on LCD polarizability decomposition. This method is implemented for SCFTYP=RHF or ROHF and LOCAL=BOYS or RUEDNBRG. (default=.FALSE.)

POLANG =flag to choose units of localized polarizability output. The default is Angstroms3, while false will give Bohr3. (default=.TRUE.)

ZDO =flag for LCD analysis of a composite wave function, given in a $VEC group of a van der Waals complex, within the zero differential overlap approximation. The MOs are not orthonormalized and the intermolecular electron exchange energy is neglected. In addition, the molecular overlap matrix is printed out. This is a very specialized option.

(default = .FALSE.)

•The remaining keywords can be used to define the nuclear part of an LCD. They are usually used to rectify mistakes in the automatic definition made when MOIDON=.TRUE. The index defining the LMO number then refers to the reordered list of LMOs.

NNUCMO = array giving the number of nuclei assigned to a particular LMO.

IJMO =is an array of pairs of indices (I,J), giving the row (nucleus I) and column (orbital J) index of the entries in ZIJ and MOIJ.

MOIJ =arrays of integers K, assigning nucleus K as the site of the Ith charge of LCD J.

ZIJ =array of floating point numbers assigning a charge to the Ith charge of LCD J.

IPROT =array of integers K, defining nucleus K as a proton.

DEPRNT =a flag for additional decomposition printing, such as pair contributions to various energy terms, and centroids of the Ruedenberg orbitals. (default = .FALSE.)

For hints about localizations, and the LCD energy decomposition, see the 'further information' section.

Formatted transformed two-electron Coulomb and Exchange integrals as punched during a LOCAL=RUEDNBRG run. If this group is present it will automatically be read in during such a run and the two-electron integrals do not have to be re-transformed. This group is especially useful for EDCOMP=.TRUE. runs when the localization has to be repeated for different definitions of nuclear LCDs.

$ELMOM group (not required)

This group controls electrostatic moments calculation.

IEMOM = 0 skip this property

1 calculate monopole and dipole (default)

2 also calculate quadrupole moments

3 also calculate octupole moments

WHERE = COMASS center of mass (default)

NUCLEI at each nucleus

POINTS at points given in $POINTS.

OUTPUT = PUNCH, PAPER, or BOTH (default)

IEMINT = 0 skip printing of integrals (default)

1 print dipole integrals

2 also print quadrupole integrals

3 also print octupole integrals

-2 print quadrupole integrals only

-3 print octupole integrals only

The quadrupole and octupole tensors on the printout are formed according to the definition of Buckingham. Caution: only the first nonvanishing term in the multi- pole charge expansion is independent of the coordinate origin chosen, which is normally the center of mass.

$ELPOT group (not required)

This group controls electrostatic potential calculation.

IEPOT = 0 skip this property (default)

1 calculate electric potential

WHERE = COMASS center of mass

NUCLEI at each nucleus (default)

POINTS at points given in $POINTS

GRID at grid given in $GRID

PDC at points controlled by $PDC.

OUTPUT = PUNCH, PAPER, or BOTH (default)

This property is the electrostatic potential V(a) felt by a test positive charge, due to the molecular charge density. A nucleus at the evaluation point is ignored. If this property is evaluated at the nuclei, it obeys the equation

sum on nuclei(a) Z(a)*V(a) = 2*V(nn) + V(ne).

The electronic portion of this property is called the diamagnetic shielding.

$ELDENS group (not required)

This group controls electron density calculation.

IEDEN = 0 skip this property (default)

= 1 compute the electron density.

MORB =The molecular orbital whose electron density is to be computed. If zero, the total density is computed. (default=0)

WHERE = COMASS center of mass

NUCLEI at each nucleus (default)

POINTS at points given in $POINTS

GRID at grid given in $GRID

OUTPUT = PUNCH, PAPER, or BOTH (default)

IEDINT = 0 skip printing of integrals (default)

1 print the electron density integrals

$ELFLDG group (not required)

This group controls electrostatic field and electric field gradient calculation.

IEFLD = 0 skip this property (default)

1 calculate field

2 calculate field and gradient

WHERE = COMASS center of mass

NUCLEI at each nucleus (default)

POINTS at points given in $POINTS

OUTPUT = PUNCH, PAPER, or BOTH (default)

IEFINT = 0 skip printing these integrals (default)

1 print electric field integrals

2 also print field gradient integrals