A simple transferable interatomic potential model for binary oxides applied to bulk αal₂O₃ and the (0001) αal ₂O₃ surface

A simple transferable potential for binary, highly ionic oxides is derived from a previous work. In this new potential the van der Waals terms involving cations and the cation-cation short-range repulsive interactions do not appear explicitly. The potential parameters of this new model are optimised for α-Al2O3, MgO and CaO. Good agreement between theory and experiment is obtained for the structural parameters and lattice energies. The potential is then employed to study the relaxation of the Al-terminated (0 0 0 1) α-Al2O3 surface as well as the dynamics of this surface at non-zero temperatures using the molecular dynamics method. Here it is shown that the new potential predicts a relaxation of the (0 0 0 1) α-Al2O3 surface which is consistent with experiment and shell model calculations. Finally, the calculated dynamical features of the (0 0 0 1) α-Al2O3 surface are explained in terms of a combination of the loss of translational symmetry and the resulting relaxation of the surface atoms.