Cancellation of the orthogonality charge from the structure-dependent energy of a metal

Abstract

The orthogonality charge is defined as the difference between the square of the true wave function and the wave function of the pseudopotential equation. It is shown that the various contributions of the orthogonality charge to the structure-dependent energy of a metal can be grouped so that they cancel out of the final result. Several papers in the literature dealing with ion–ion potentials, crystal structures, or phonon frequencies have not included all of these contributions.