A semi-empirical effective interionic potential model has been parameterized to investigate UO 2 by molecular dynamics simulation technique. The simulations were performed in the constant pressure–temperature ensemble between 300 K–3200 K at 100 K intervals. The pair distribution functions and coordination numbers signal the onset of structural changes at temperatures in accord with the Bredig transition and melting. The oxygen ion diffusion coefficients calculated from the mean square displacements markedly increase the liquid like value at T > 2100 K . The transition to the superionic state and melting are well reproduced within the limitations of a rigid ion potential.

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Classical molecular dynamics simulation calculations of silver bromide, AgBr, and silver chloride, AgCl. in constant volume-energy (NVE) and constant pressure-temperature (NPT) ensembles have been performed. The temperature dependence of linear thermal expansion and molar heat capacities at constant volume and pressure have been presented at solid and liquid phases. The anomalous behavior of these properties about 200 K below the melting temperatures has been analyzed within the frame of the onset of the transition to the superionic phase.

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