Atomistic simulations of B1–B2 phase transition in KCl based on inversion pair potentials

Abstract

Based on the Chen–Möbius lattice inversion, interionic pair potentials are derived from the pseudopotential total energies of KCl in B1, B2, B3 and one tetragonal structures. In terms of inversion potentials, four different transition pathways have been presented to describe the B1–B2 phase transition by using unit cells with different symmetric restrictions and sizes. Although the intermediate states are obviously different along the four pathways, the simulations indicate that the essence of phase transition is reflected by a Buerger mechanism. With more independent variables than the Buerger and WTM mechanisms, the present potentials predict that the transition path is formed by a series of states with different subgroup symmetries between Fm 3 ̄ m and Pm 3 ̄ m . This indicates that fewer symmetry restrictions will introduce intermediate structures with low symmetry along the transition path. One of the predicted intermediate structures is in good agreement with that found in the B1–B2 phase transition of AgCl. The exhibited transition characters also indicate that the present inversion pair potentials are appropriate in exploring the B1–B2 phase transition in KCl crystal.