Volume 2 Chapter 7 Numeric Sub-menu *BRV1
*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
