Embedding procedure for cluster calculations of ionic crystals

An embedding procedure suitable for Hartree-Fock studies of ionic systems is presented and implemented on the semiempirical level. In this approach model clusters are embedded in finite fields of pseudoatoms with average self-consistent orbital occupation numbers or fixed orbital occupation numbers for best charge equilibration of cluster atoms. These pseudoatoms are of the same kind and described with the same set of parameters as the real cluster atoms. The implementation in the semiempirical self-consistent field molecular orbital method SINDO1 is described. Calculations are performed for the systems TiO2 and MgO and the influence of the embedding on geometry and electronic structure is discussed. (C) 1996 American Institute of Physics.