SOFTWARE FOR LATTICE IDENTIFICATION IN G-6

Herbert J. Bernstein, Bernstein+Sons, 5 Brewster Lane, Bellport, NY 11713-2803, USA and Lawrence C. Andrews, 3660 Crestline Way, Soquel, CA 19073, USA.

We present the current state of software for Bravais lattice identification in G-6, based on a Fortran program which will accept experimental cell information on-line or from mmCIF or PDB format data files.

The coordinate system of G-6, defined by (a,a), (b,b), (c,c), 2(b,c), 2(a,c), 2(b,c) is one in which a meaningful measure for quality of lattice identification is provided by Euclidean distances from appropriate linear subspaces. A modest combinatorial complexity is introduced by the need to evaluate multiple alternative distances not only from a given cell, but from nearby nearly-reduced cells. If the original reduced cell is not highly skewed the identification of a minimal distance requires only one to two shells of operations from the group of reduction transformations.