Data Item _pdbx_reflns_twin.type

General

Item name
_pdbx_reflns_twin.type
Category name
pdbx_reflns_twin
Attribute name
type
Required in PDB entries
no
Used in current PDB entries
Yes, in about 0.04 % of entries

Item Description

There are two types of twinning: merohedral or hemihedral non-merohedral or epitaxial For merohedral twinning the diffraction patterns from the different domains are completely superimposable. Hemihedral twinning is a special case of merohedral twinning. It only involves two distinct domains. Pseudo-merohedral twinning is a subclass merohedral twinning in which lattice is coincidentally superimposable. In the case of non-merohedral or epitaxial twinning the reciprocal lattices do not superimpose exactly. In this case the diffraction pattern consists of two (or more) interpenetrating lattices, which can in principle be separated.

Data Type

Data type code
line
Data type detail
char item types / multi-word items ...
Primitive data type code
char
Regular expression
[][ \t_(),.;:"&<>/\{}'`~!@#$%?+=*A-Za-z0-9|^-]*

Controlled Vocabulary

Allowed Value Details
epitaxial
hemihedral
merohedral
non-merohedral
pseudo-merohedral
tetartohedral

Controlled Vocabulary at Deposition

Allowed Value Details
epitaxial .
hemihedral .
merohedral .
non-merohedral .
pseudo-merohedral .
tetartohedral .