Model studies of the Si(111)2 × 1 surface by the pseudofunction method

Abstract The recently developed pseudofunction (PSF) slab calculational method is used to study the electronic structure and total energy of the uniformly relaxed, buckling, and Pandey's chain-like reconstruction of the Si(111)2 × 1 surface. It is found Pandey's π bonded chain model is the most favorable by − 0.54 eV surface atom relative to the ideal surface. For the uniformly relaxed case the equilibrium relaxation and the vibrational excitation agree well with generalized valence bond (GVB) calculations. Pandey's chain model yields a surface-resonance band resembling well that of Northrup and Cohen from Γ to J′. An equilibrium surface chain bond length of 2.28 A is obtained with a bare 6-layer slab. However, an expanded or unstable surface chain is found when the dangling bonds on opposite side surface are saturated with either an H layer or a Cl layer. Thus, results for thin semiconductor slabs may be model-dependent.