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

We show how quasiharmonic lattice dynamics, Monte Carlo, molecular dynamics and ab initio techniques are increasingly able to provide valuable informa tion concerning the behaviour of perfect and disordered polar solids over a broad range of temperatures and pressures. A wide range of examples includ es (i) the thermodynamics of the pressure-induced phase transformation in M gF2 between the rutile and fluorite structures, (ii) the negative thermal e xpansion of ZrW2O8, (iii) surface and defect free energies as a function of temperature, (iv) solid solutions of oxides and silicates, (v) possible me chanisms for the B1-B2 phase transition in SrO, and (vi) MnO and NiO at hig h pressure. Particular attention is paid to the merits and limitations of t he various methodologies and the advantages of using a combination of these techniques to obtain a broader understanding of particular problems.