Oxide potentials from ab initio molecular dynamics:: An assessment of their transferability

An aspherical ion model (AIM) description of interatomic interactions in alkaline earth oxides MgO, CaO, SrO, and BaO has been obtained. The parameters were determined by matching the forces predicted by the models to those calculated from an ab initio dynamics calculation in finite temperature simulations. The models were shown to be transferable in the sense that they offered equally accurate descriptions of the pure materials over very wide ranges of temperature and pressure and in phases with different coordination number. In the present paper, more wide-ranging transferability considerations are pursued. First, we check transferability between chemically related substances: we transform the model for CaO into a potential for BeO by scaling parameters according to the changes in ion sizes and polarizabilities. Second, we test transferability upon compound formation, by combining the MgO and CaO potentials in order to describe the interatomic interactions in MgO-CaO solid binary mixtures. The results show that the proposed models are able to provide a good description of interatomic interactions in both cases. The calculations demonstrate that the AIM represents the different contributions to the interionic forces faithfully and that the force-matching procedure finds physically meaningful values for the parameters therein. (C) 2003 American Institute of Physics.