Lattice inversion for interionic pair potentials

Abstract

The ab initio total energies of alkali chloride crystals in B1 (rock salt), B2 (CsCl-type), B3 (zinc blende) and P4/mmm structures are calculated by ultrasoft pseudopotential method in this paper. Based on the different combinations of these total energies, the effective charges on ions are determined for long-range Coulomb interaction, and the short-range potential curves are obtained by the lattice inversion method. As the test for the quality of potentials, the static properties of ACl in the rock salt phase are calculated. The results are in good agreement with the experimental data. And the calculated lattice energies for ACl in wurtzite, CuAu, NiAs, and litharge structures are consistent with the predictions of pseudopotential calculations. In terms of the molecular dynamics simulations, the temperature dependences of volume, bulk modulus, and elastic constants are also investigated from room temperature to 800 K, the results are in good agreement with the experimental values. This indicates that the new interionic potentials are valid over a wide range of interionic separations and coordination numbers.