Theoretical studies of atomic vibrations on theSi(001)(2×1)surface

Abstract

We present adiabatic bond-charge model studies of surface-phonon modes on the symmetric and asymmetric dimer models of the $\mathrm{Si}(001)(2\ifmmode\times\else\texttimes\fi{}1)$ surface. The structural and electronic information necessary for these calculations is obtained using the ab initio pseudopotential method. We find that dimerization leads to the formation of new peaks in the phonon density of states. In particular, the peak in the stomach gap at around 30 meV is a strong signature of dimer formation.