Structural, electronic, and dynamical properties of theC(001)−(2×1)surface

Abstract

We have made theoretical investigations of the atomic geometry, electronic structure, and lattice dynamics of the $\mathrm{C}(001)\text{\ensuremath{-}}(2\ifmmode\times\else\texttimes\fi{}1)$ surface. The atomic geometry and electronic structure have been calculated by using the local density approximation of the density functional theory and ab initio pseudopotentials. Using our calculated atomic and electronic structures, surface lattice dynamics was studied by employing two different approaches: a linear response approach based on density functional perturbation theory, and an adiabatic bond-charge model. The phonon dispersion curves obtained from the two models are compared against each other in detail. In general, results from both models are in agreement with each other, with small differences due mainly to differences in the conceptual natures of these models. Our results from both methods are in good agreement with recent electron energy loss spectroscopy measurements. We have also provided a comparison of a few characteristic phonon modes on this surface with those on the $\mathrm{Si}(001)\text{\ensuremath{-}}(2\ifmmode\times\else\texttimes\fi{}1)$ and $\mathrm{Ge}(001)\text{\ensuremath{-}}(2\ifmmode\times\else\texttimes\fi{}1)$ surfaces.