Surface interactions and surface dynamics on a clean reconstructed W(100)

Abstract

We have extended our study of the surface dynamics of a clean W(100) to the region T${\mathit{T}}_{\mathit{c}}$. We have determined the surface phonon dispersion relations using a quasiharmonic approximation at low temperatures and a method of critical dynamics near ${\mathit{T}}_{\mathit{c}}$. We demonstrate here how the phonon band gap opens at the surface Brillouin-zone boundary, as the surface goes into the c(2\ifmmode\times\else\texttimes\fi{}2) phase. We also show how the surface phonon excitation differs from the harmonic picture under the presence of strong anharmonic interactions and large critical fluctuations.