*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 rhombohedralThe 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

Volume 2 Chapter 7 Numeric Sub-menu *CASNUMBER.