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 using the local-density approximation ~LDA!. Wave functions are localized about each ion, resulting in a single-particle Schrödinger’s equation for each ion. To simplify the calculation, we spherically average the potential energy in each of these equations. The electron density is determined from the self-consistent solution of these equations. SSCAD scales as order N and runs very fast, even for crystals with large unit cells. We discuss some of the limitations of SSCAD, and we give examples of using SSCAD to determine crystalline structure, phonon dispersion, elastic moduli, and charge transfer. @S0163-1829~96!07635-7#