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*ALSUN

*ALSUN is used to define the puckering parameters of a 5-membered ring in terms of the amplitude and phase angle of pseudorotation, as described by Altona and Sundaralingam, J.Amer.Chem.Soc. 94, 8205-8212 (1972).

Example

• Select *ALSUN

• Select or type items for *ALSUN. If necessary reselect *ALSUN to
  end input.
  Select CANCEL to cancel command.

• Select atom number 1

• 1 appears in the dialogue area

  A red + appears at atom 1 in the fragment.

• Select in turn atoms 2 3 4 5

  As each atom is selected a red + appears at the atom in the fragment.

  After the selection of the fifth atom these red crosses disappear.

• In the dialogue area we now have:

  DEFINE, *ALSUN,
  Input *ALSUN parameter name no.  1

• Type TAUMAX <RETURN>

• In the dialogue area we now have:

  DEFINE, *ALSUN, TAUMAX,
  Input *ALSUN parameter name no.  2

• Type PHI <RETURN>

• In the summary area we now have:

  *ALSUN  TAUMAX  PHI  1  2  3  4  5

  This line is displayed in green to indicate that it is a DEFINE command.

  In the dialogue area we now have the "home" prompt:

  Search for ALL crystal fragments
  OVERLAP of crystal fragments permitted
  Select a menu command or TO-BUILD to return to the BUILD menu.

  The resultant command in the instruction document is:

  DEFINE  *ALSUN  TAUMAX  PHI  1  2  3  4  5

Note also that the phase angle of pseudo-rotation is not normalised by a MOD(PHASE,360) function and may, therefore, span the range 0-360 degrees.If required, the MOD function can be applied by a TRANSFORM command on parameter no.2.

Related Command

DEFINE *CREMER

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Volume 2 Chapter 3 3D-Constrain Sub-menu ATOM-LABEL.