SPHERICAL SELF-CONSISTENT ATOMIC DEFORMATION MODEL FOR FIRST-PRINCIPLES ENERGY CALCULATIONS IN IONIC CRYSTALLINE SOLIDS

We present a first-principles method [called spherical self-consistent atomic deformation (SSCAD)] for calculating the energy per unit cell in ionic crystalline solids. SSCAD is a density-functional method usin g the local-density approximation (LDA). Wave functions are localized about each ion, resulting in a single-particle Schrodinger's equation for each ion. To simplify the calculation, we spherically average the potential energy in each of these equations. The electron density is d etermined from the self-consistent solution of these equations. SSCAD scales as order N and runs very fast, even for crystals with large uni t cells. We discuss some of the limitations of SSCAD, and we give exam ples of using SSCAD to determine crystalline structure, phonon dispers ion, elastic moduli, and charge transfer.