rmat file format

The rmat file contains the reciprocal axes matrix.
The RMAT keyword and data are obligatory, the other keywords are optional.
Lines starting with # are ignored.

RMAT

Syntax: RMAT bravaistype
Status: Required
bravaistype is one of ABCFIPR.
The matrix is build by the components of the reciprocal axes (in the laboratory system) in columns with all goniostat angles set to zero.

a^*_x	b^*_x	c^*_x
a^*_y	b^*_y	c^*_y
a^*_z	b^*_z	c^*_z

Example:

RMAT P
  0.09404740  0.06127740 -0.03415260
  0.07703950 -0.07504390 -0.00808750
 -0.06476710 -0.02511310 -0.05923030

TMAT

Syntax: TMAT bravaistype pg
Status: optional
bravaistype is one of ABCFIPR.
pg is the pointgroup. See the list of pointgroups.
The transformation matrix can be applied to a dmat (direct axes matrix, the inverse of the rmat) or a reflection indices vector.
The elements of the matrix are on the following line(s)

T₁₁	T₁₂	T₁₃
T₂₁	T₂₂	T₂₃
T₃₁	T₃₂	T₃₃

Example:

RMAT P
  0.09404740  0.06127740 -0.03415260
  0.07703950 -0.07504390 -0.00808750
 -0.06476710 -0.02511310 -0.05923030
TMAT P 2/m
  1.00000000  0.00000000  0.00000000
  0.00000000  0.00000000 -1.00000000
  0.00000000  1.00000000  0.00000000

CELL

Syntax: CELL a b c alpha beta gamma
Status: optional
These numbers are for documentation purposes only. The actual cell parameters are always extracted from the rmat.

SIGMA

Syntax: SIGMA a b c alpha beta gamma
Status: optional
Sigma's of cell parameters.

QVECTYPE

Syntax: QVECTYPE NONE/MODULATED/COMPOSITE
Status: optional
Sets the Qvectype. The default is NONE if no QVEC's are defined and MODULATED is QVEC's are defined.

QVEC

Syntax: QVEC fh fk fl [order]
Status: optional
Adds a qvector to the qvector list. fh fk fl are fraction numbers in terms of a^*, b^* and c^*
qvectors are combined to qvector combinations (QVC).
The optional order is the maximum order of the qvector. If no QVC records are available, a set of qvector combinations will be generated using order.

QVC

Syntax: QVC n1 n2 n3....
Status: optional
Defines a qvector combinaton. The number of arguments must be equal to the number of qvectors. If no QVC's are defined, a set of qvector combinations will be generated.

QVECRADIUS

Syntax: QVECRADIUS f
Status: optional
Overrules the maximum qvector radius (QVR).
If no qvector combinations (QVC) are defined, they will be generated.

If only one qvector is defined, the order of that qvector determines the the limits of the generated set of qvector combinations.
If two or more qvectors are defined, the orders of the qvectors and the maximum qvector radius (QVR) limit the generation of qvector combinations.
- If no QVECRADIUS is specified, a default one will be calculated:
  For every qvector: multiply the qvector components with the corresponding order and multiply the result with the rmatrix.
  v = R·(order*qv)
  The resulting vector v is now defined in the laboratory system, and it's length 1/d = 2*sin(θ)/λ
  The (default) QVR is set to the maximum value of 1/d of the contributing qvectors.
- Combinations of qvectors are generated, each qvector limited between its own order.
- The resulting combination is only allowed if its 1/d is less than the maximum QVR.