From Online Dictionary of Crystallography
Revision as of 18:07, 5 April 2007 by MassimoNespolo
For a point group P a form is a set of all symmetrically equivalent "elements", namely:
- in vector space, a crystal form or face form is a set of all symmetrically equivalent faces;
- in point space, a point form is a set of all symmetrically equivalent points.
The polyhedron or polygon of a point form is dual to the polyhedron of the corresponding face form, where "dual" means that they have the same number of edges but the number of faces and vertices is interchanged.
- Chapter 10 in the International Tables for Crystallography, Volume A