Volume 2 Chapter 7 Numeric Sub-menu *BRV1

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*BRV2

Function

*BRV2 is used to test for entries corresponding to a specified Bravais lattice for the reduced unit cell.

CSD Contents

The 14 Bravais lattice types are:

1  triclinic                     8 simple tetragonal
2  simple monoclinic             9 body-centred tetragonal
3  base-centred monoclinic      14 hexagonal
10 simple orthorhombic           5 simple cubic
11 base-centred orthorhombic     6 body-centred cubic
12 body-centred orthorhombic     7 face-centred cubic
13 face-centred orthorhombic     4 rhombohedral
The Niggli reduced cell is calculated at the CCDC and incorporated into the CSD.

For non-crystallographers it is sufficient to state that the Niggli reduction process transforms the unit cell reported by the author to a "standard" cell, according to a set of mathematical conditions.

Graphics QUEST3D Procedure

Select *BRV2 from the NUMERIC sub-menu and respond to the standard numeric prompts.

Basic QUEST Procedure

Ex.

T1 *BRV2 .EQ. 13

This will register hits for all entries whose reduced cell has a face-centred orthorhombic Bravais lattice.

Related Bit Screens

Two sets of bit screens are available for lattice types and crystal systems:

110 lattice type   unknown          102 crystal system is     unknown
111                primitive        103                       anorthic (triclinic)
112                A-centred        104                       monoclinic
113                B-centred        105                       orthorhombic
114                C-centred        106                       tetragonal
115                F-centred        107                       hexagonal
116                I-centred        108                       cubic
117                rhombohedral     109                       rhombohedral

Ex.

SCRE 114

This will register hits for all entries whose lattice type is C-centred.

Ex.

SCRE 107

This will register hits for all entries whose crystal system is hexagonal.

Related Keywords

*BRV1

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Volume 2 Chapter 7 Numeric Sub-menu *CASNUMBER.