Charge shift as a criterion of correctness of the surface electronic structure LCAO calculations

An essential problem in semiempirical LCAO calculations of the surface elec tronic structure of compound semiconductors is the dependence of the result s on the values of Hamiltonian parameters. To be more specific, various set s of Hamiltonian parameters, equally well reproducing the dispersion curves and the main band gap of crystal volume, lead to differences in the surfac e-state dispersion curves which, in turn, influence the Fermi level positio n. As an example, the (001) surface of a strongly ionic beta -GaN semicondu ctor is considered. On the basis of the obtained results, it is suggested t hat the value of a charge shift can be used as an additional criterion of t he correctness of Hamiltonian parametrization. (C) 2001 Elsevier Science Lt d. All rights reserved.