Ionic solids at elevated temperatures and/or high pressures: lattice dynamics, molecular dynamics, Monte Carlo and ab initio studies

Abstract

We show how quasiharmonic lattice dynamics, Monte Carlo, molecular dynamics and ab initio techniques are increasingly able to provide valuable information concerning the behaviour of perfect and disordered polar solids over a broad range of temperatures and pressures. A wide range of examples includes (i) the thermodynamics of the pressure-induced phase transformation in MgF₂ between the rutile and fluorite structures, (ii) the negative thermal expansion of ZrW₂O₈, (iii) surface and defect free energies as a function of temperature, (iv) solid solutions of oxides and silicates, (v) possible mechanisms for the B1–B2 phase transition in SrO, and (vi) MnO and NiO at high pressure. Particular attention is paid to the merits and limitations of the various methodologies and the advantages of using a combination of these techniques to obtain a broader understanding of particular problems.