AB-INITIO CALCULATION OF GEOMETRY AND BONDING FOR OVERLAID AND INLAIDMODELS OF SI(001) SB(0.25ML)-C(4X4)/

Recent experimental work has revealed the existence of a c(4 x 4) reco nstruction of the Si(001)-Sb surface in the Sb coverage range between 0.2 and 0.3 monolayers. The best fit to the experimental data was foun d with a structural model in which Sb dimers are adsorbed above the Si (001) dimer rows (overlaid above row structure), although a structure in which Sb dimers are incorporated into the top Si layer (inlaid stru cture) also fitted reasonably well. In a previous theoretical work we have shown the overlaid geometry to have the lowest surface free energ y of a number of structural models considered, with the inlaid structu re coming a close second. In this work we present a detailed discussio n of bonding information for both of these models. (C) 1998 Elsevier S cience B.V. All rights reserved.