Maximal symmetry transition paths for reconstructive phase transitions

Abstract

An essential part of the description of a reconstructive phase transition consists inthe determination of the so-called transition path, which defines the possibleatomic displacements and lattice strains that occur during the transformation. Wepresent a systematic procedure for the determination of possible transition paths inphase transitions with no group–subgroup relation between their phases. It isassumed that the transformation involves, at least locally, an intermediate statedescribed by a common subgroup of the symmetry groups of the two end phases.The possible mappings between the end structures are restricted by symmetryconstraints following from the occupied atomic orbits, and tolerances for latticestrains and atomic displacements. The concept of maximal symmetry transitionpaths is used for the classification of the different symmetry allowed transitionpaths. The application of the procedure is illustrated by the determination ofmaximal symmetry transition paths for the transformations from wurtzite torocksalt, zincblende to rocksalt and rocksalt to caesium chloride structure types.