Volume 2 Chapter 11 Text Menu *FORMULA

Function

*FORMULA is used to test the complete formula record.

CSD Contents

To use *FORMULA correctly it is essential to have a knowledge of the syntax conventions used for the storage of formulae in the CSD. The most important are :

within each residue the elements are ordered in the sequence C, H, D, others alphabetically
one residue formula is separated from the next by ,

Examples of formula records are:

C6 H4 Br1 N1 O2
C1 H1 D1 Cl2
C6 H6 O2,C1 H4 N2 O1
C2 H2 O4,2(H2 O1)
C9 H12 N2 O5 S1,1.5(H2 O1)
C29 H38 O11,x(H2 O1)
2(C1 H1 O2 1-),Sr1 2+
(C3 H3 O6 Sc1)n
(C6 H12 Ce2 O18)n,4n(H2 O1)

Graphics QUEST3D Procedure

Select *FORMULA from the TEXT sub-menu and respond to the standard text prompts.

Basic QUEST Procedure

Ex.1

T1 *FORM C24 H57 B9 N7 P3

This will register hits for entries having the specified formula. However it will also hit formulae such as:

C24 H57 B9 N7 P3 S1
C24 H57 B9 N7 P31
C24 H57 B9 N7 P3,H2 O1

etc.

Note that *FORMULA searching is very slow but can be speeded up by also specifying an *ELEMENT test or appropriate SCRE instructions.

Ex.2

(a)

T1 *FORM C10 H10 Ni1
QUES T1

(b)

T1 *ELEM Ni
T2 *FORM C10 H10 Ni1
QUES T1

(c)

SCRE 10
T1 *FORM C10 H10 Ni1
QUES T1

(b) and (c) will provide much faster searches than (a).

Related Keywords

*NRESIDUES, *MAXATOMICNO, *ELEMENT, *SUMFORMULA, *RESFORMULA, *RESIDUE

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Volume 2 Chapter 11 Text Menu *JRNL .