General procedure for obtaining microscopic mechanisms of reconstructive phase transitions in crystalline solids

Abstract

A procedure for obtaining possible microscopic mechanisms for reconstructivephase transitions in crystalline solids is described. Both strainsand atomic displacements are considered, and the procedure includesuser input of allowed strain tolerance, nearest-neighbor distances,and unit-cell size change. This method has been implemented in acomputer program comsubs. We apply comsubs to the pressure-inducedphase transition in NaCl and obtain 12 possible mechanisms, two ofwhich are those proposed earlier by Buerger and Watanabe, respectively.Furthermore, we show how to use energy calculations to determinethe height of the energy barrier for the transition.