OPTIMUM WIDTHS OF DIMER VACANCY LINES ON SI(100)-(2X1)

We have used the ab initio multicenter molecular-dynamics method to ca lculate the surface energies of dimer vacancy lines (DVL's) formed on the Si(100)-(2x1) surface as a result of sputtering or etching. Our re sults show that the optimum widths of the DVL's perpendicular to the d imer rows are two and three missing dimers. Our results also show that at higher vacancy concentrations, DVL's parallel to the dimer rows (s ometimes also known as ''vacancy islands'') with widths greater than t hree missing dimers are favored over the perpendicular DVL's. Both of these results are in agreement with experimental observations.