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 the structures and representations of crystallographic space groups. The programs, written in PASCAL and C, are made user friendly by additional 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 identifies all domain states and finds inter alia (i) symmetry groups of all domain states in algebraic form as a conjugate subgroup stratum, (ii) all operations that transform a given domain state into another domain state, (iii) classes of crystallographically equivalent domain pairs, (iv) symmetry groups of ordered and unordered domain pairs. As an illustrative example software results for the triply commensurate charge-density-wave domain states in the 2H polytype TaSe 2 are presented.