LCAO SECULAR DETERMINANT PROGRAM

Abstract

The report describes a computer program designed to set up the secular determinant arising from an energy band calculation in the LCAO (Linear Combination of Atomic Orbitals) approximation. The program determines which transfer integrals vanish, and which are related; further, it computes the appropriate structure factor (which contains the momentum dependence) for each entry in the secular determinant. This program can handle arbitrary crystal symmetry, unit cells with many inequivalent atoms, interactions involving up to fourth-nearest neighbors, and a choice of s-, p-, and/or d-orbitals on the various inequivalent atoms. The transfer integrals are left as parameters to be determined from the eigenvalues corresponding to special symmetry points in the Brillouin zone.