Energy landscapes and thermodynamics of bulk mixed oxide materials

This presentation focuses on the energy landscapes of bulk oxide materials, modeled at the level of empirical potentials. A specific (benchmark) example consists of a mixture of calcium-oxide and magnesium oxide (CaO/MgO). The bulk form of this disordered system is studied using a super-cell with periodic boundary conditions. After implementing the potentials into the GMIN global optimisation code and the OPTIM code for transition state calculations, a host of energy landscape methods becomes available. Databases of minima and transition states have been generated in order to produce a disconnectivity graph. Attempts have been made to calculate the thermodynamic properties of the CaO/MgO system using the recently developed Basin Sampling methodology [1]. The first step in such a calculation is determining the density of minima and this proved to be very difficult to achieve with the Wang-Landau algorithm used in the standard implementation of the Basin Sampling method. The author hopes to achieve better results with an improved version of the Basin Sampling method using Parallel Tempering as the underlying sampling algorithm.