SI(001) B SURFACE RECONSTRUCTION

We have used ab initio total-energy calculations to study the various possible structures resulting from surface reconstruction of Si(001) s urface due to half a monolayer coverage of adsorbed B. The ranking of energies for the different structures considered can be attributed to the concentration of strains. The structures that we find to have the lowest energy are compared with the results of a recent scanning tunne ling microscopy (STM) study. None of the structures, including those p roposed by the authors of the STM work, accounts satisfactorily for th e STM features reported.