SYMMETRY_FIND_ORI

SYMMETRY_FIND_ORI = False is used to declare that the origin of the input POSCAR file is already one of the highest-symmetry points in the cell. The symmetry search is then restrained to the origin. Only the origin will be tested as a rotation axis, and only planes passing through the origin will be tested as the main mirror or glide planes.

Default: SYMMETRY_FIND_ORI = True

Syntax:

SYMMETRY_FIND_ORI = False

Acceptable values: True, False, true, false, T, F, t, f

Changed in version 0.8.0: Up to and including viperleed.calc version 0.7.2 the default was only True if no symmetry group was defined in the POSCAR header and False otherwise. This was changed in newer versions as it could introduce errors if the POSCAR was edited, but the symmetry group comment was left unchanged.

SYMMETRY_FIND_ORI = False is intended for user input files only in very large cells that do not have at least one low-occupancy sublayer. In such cells, the symmetry search can sometimes time out due to the very high number of candidate symmetries that need to be tested. If the user is aware of the highest-symmetry point in the cell, moving the origin there beforehand and setting SYMMETRY_FIND_ORI = False is recommended.

For POSCAR files optimized by ViPErLEED, the origin has been moved to a point of highest symmetry. These files can be recognized by the POSCAR header, which includes the symmetry group.