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Abstract

A fully flexible ionic interaction model for alumina, Al2O3, is developed. The model accounts for ionic polarizability and shape deformations up to the quadrupolar level. The parameters of the interaction potential are optimized by reference to ab initio density-functional theory (DFT)-based electronic structure calculations. Two potential models, derived from DFT using the local density approximation (LDA) and the generalized gradient approximation (GGA), respectively are compared. Both potentials reproduce accurately bulk and surface properties of the corundum phase, and transfer well over a wide range of pressures and temperatures. The sequence of high pressure polymorphic phases is predicted correctly. The potential derived from LDA-DFT also gives an excellent description of the melt whereas the potential fitted to GGA-DFT considerably overestimates the equilibrium molar volume of the melt. The accuracy of the potentials regarding, e.g., lattice parameters or elastic constants is comparable to the respective electronic structure method.