Theory of inelastic electron vibrational spectroscopy of W(001) at finite temperature.

Abstract

The temperature-dependent dipole-active phonons of the clean c(2\ifmmode\times\else\texttimes\fi{}2) W(001) surface, across the reconstruction phase transition at ${\mathrm{T}}_{\mathrm{c}}$\ensuremath{\simeq}250 K, are studied by molecular dynamics. Our calculated inelastic electron rate shows a reconstruction-related low-temperature peak, corresponding to a mostly second-layer surface phonon of high frequency. This mode disappears above ${\mathrm{T}}_{\mathrm{c}}$, because of fluctuations of the distortion phase angle, and provides a new explanation of the recent electron-energy-loss spectroscopy data of Woods and Erskine.