PC SOFTWARE FOR CRYSTALLOGRAPHIC SPACE-GROUPS AND ITS APPLICATION IN SYMMETRY ANALYSIS OF DOMAIN-STRUCTURES

An integrated package of programs has been developed to investigate th e structures and rep resentations of crystallographic space groups. Th e programs, written in PASCAL and C, are made user friendly by additio nal programs using the Oakland C-scape Interface Management System. A Microsoft Windows version of the software is currently being developed using Borland Delphi. For a given phase transition the software ident ifies all domain states and finds inter alia (i) symmetry groups of al l domain states in algebraic form as a conjugate subgroup stratum, (ii ) all operations that transform a given domain state into another doma in state, (iii) classes of crystallographically equivalent domain pair s, (iv) symmetry groups of ordered and unordered domain pain. As an il lustrative example software results for the triply commensurate charge -density-wave domain states in the 2H polytype TaSe2 are presented.