ENERGY-BAND CALCULATIONS USING THE LCAO BASES AND EMPIRICAL PSEUDOPOTENTIALS

The method of LCAO (Linear combination of atomic orbitals) using the e mpirical pseudopotentials of Cohen and Bergstresser (CB) is examined t o calculate the energy-band structures of the Si, Ge, Sn, and GaAs sem iconductors by the discrete variational method. The LCAO Bloch basis f unctions are constructed from neutral atomic orbitals calculated self- consistently by using the Hartree-Fock-Slater method. The results are compared to the local empirical pseudopotential results of CB, and we find that the minimal basis set can not produce good results. We inclu de excited orbitals in the basis set and obtain good agreement with th e results of CB. The pseudopotential form factors are adjusted when ne cessary. We find that the LCAO basis set can produce energy-band struc tures which are as good as those produced by the plane-wave basis set.