FIRST-PRINCIPLES LOCAL-ORBITAL STUDY OF THE BORON-INDUCED RECONSTRUCTION OF SI(001)

A self-consistent multicenter local-orbital formalism is used to inves tigate the total energy and atomic equilibrium positions of several st ructural models suggested for the Si(001) surface covered by half a mo nolayer of boron. Density-functional calculations based on the Harris functional approximation for the total energy are performed within the local-density approximation and the pseudopotential method. Localized atomiclike orbitals are used for the expansion of the electronic wave functions, together with the slab supercell description for the surfa ce. We focus on the identification of the structural subunits which fo rm the ordered c(4X4) reconstruction patterns recently observed by sca nning-tunneling microscopy.(STM). Our calculations favor a structural model which is different than previously proposed geometries. Moreover , the local density of surface states determined for the lowest-energy configuration agrees very well with the corrugation, lateral distribu tion, and orientation of the protrusions seen in the STM topographs. [ S0163-1829(98)04215-5].