Approximate formulation of the orthogonalized plane-wave method

An approximate method is derived for calculating the energy band of solids, analogous to the orthogonalized plane-wave method. In this method the exact condition for the orthogonality of the wave functions of valency electrons to the wave functions of the electrons of ions is replaced by a repulsive potential, determined statistically. It is shown by the example of the energy spectrum of diamond that despite the relative simplicity of this method, its results are comparable to those given by other methods. Correlation is also carried out between this method and the Phillips energy-band interpolation scheme.