GEOM - PLANES
PLANES
Computes mean planes of groups of up to 20 atoms. The program prompts the user to type the
atom labels, and asks whether the atoms are to be weighted according to the precision
of their postions or whether unit weights are required. There follows a prompt for the
option to include in the mean plane atoms related by a center of symmetry at the
crystallographic origin, in which case only the atoms in the asymmetric unit need to be
specified. In groups with any other symmetry, all equivalent positions of the atoms must
be present in the model file and explicitly referenced in the groups contents. Also, all
atoms in a group must be in the same asymmetric unit, since no symmetry
transformations or lattice translations are applied. The mean plane is defined as the
plane at right angles to the groups axis of highest moment of inertia, which is the
eigenvector of the tensor of inertia. The weighted sum of squared deviations of the
atoms from the plane is minimised.
If only two atom labels are given, the angle between the line so defined and all
other lines and plane normals are calculated.