ELECTRONIC LOCALIZED AND RESONANCE STATES OF RELAXED GAAS(110) SURFACE - AN AB-INITIO LMTO APPROACH

We present results of a comprehensive and systematic study of localize d and resonance electron surface states for an unrelaxed as well as re laxed GaAs (110) zinc-blende surfaces by employing a first-principles full-potential self-consistent linear-muffin-tin orbital method and a supercell approach with the local density approximation of density fun ctional theory. Intrinsic surface states appear in the fundamental ene rgy gap for the unrelaxed surface atoms. These intrinsic surface state s shift towards the bulk valence and conduction band region when the r elaxation of the atoms in the vicinity of the surface are considered, Localized surface and resonance states are identified and are compared with the results of other calculations and the experimental data. The results are in very good agreement with the available angle-resolved photoemission (ARPE) and inverse photoemission data. Orbital character s of localized and resonance states have been investigated. Some new s urface states around the symmetry point Gamma have been predicted for the first time which are in reasonable agreement with the ARPE data. ( C) 1998 Elsevier Science B.V. All rights reserved.