Symm_setup [mol] [cell] [symmops]
Setup for symmetry. The user is prompted for the molecule name, the unit
cell constants, and then a formatted text datablock describing the
crystallographic symmetry operators. This datablock must be named
.space_group_operators and must contain an explicit description of
all symmetry operators (including centered ones). The unit
transformation operator must be the first one defined. As everywhere
else in O, each operator consists of 12 floating point numbers,
encoding a rotation matrix and a translation matrix. The rotation matrix
is a (3 x 3) matrix store columnwise,
while the translation matrix T(i)
is a column vector, given in crystallographic fractional coordinates.
They must be stored in columns as R(11), R(21), R(31), R(12),
R(22), R(32), R(13), R(23), R(33), T(1), T(2), T(3). The
operators for space group P(21) would be
1 0 0 0 1 0 0 0 1 0 0 0followed by
-1 0 0 0 1 0 0 0 -1 0 0.5 0
Example files for the common space groups are found in the $ODAT/symm/ directory. This option creates 2 datablocks, [mol]_cell and [mol]_symmop.