Interatomic potentials for monoatomic metals from experimental data and abinitio calculations

We demonstrate an approach to the development of many-body interatomic pote ntials for monoatomic metals with improved accuracy and reliability. The fu nctional form of the potentials is that of the embedded-atom method, but th e: interesting features are as follows: (1) The database used for the devel opment of a potential includes both experimental data and a large set of en ergies of different alternative crystalline structures of the material gene rated by nb initio calculations. We introduce a rescaling of interatomic di stances in an attempt to improve the compatibility between experimental and ab initio data. (2) The optimum parametrization of the potential for the g iven database is obtained by alternating the fitting and testing steps. The testing step includes a comparison between the ab initio structural energi es and those predicted by the potential. This strategy allows us to achieve the best accuracy of fitting within the intrinsic limitations of the poten tial model. Using this approach we develop reliable interatomic potentials for Al and Ni. The potentials accurately reproduce basic equilibrium proper ties of these metals, the elastic constants, the phonon-dispersion curves, the vacancy formation and migration energies, the stacking fault energies, and the surface energies. They also predict the right relative stability of different alternative structures with coordination numbers ranging from 12 to 4. The potentials are expected to be easily transferable to different l ocal environments encountered in atomistic simulations of lattice defects. [S0163-1829(99)05005-5].