Phonon spectral densities of Cu surfaces: application to Cu(211) - art. no. 205422

Power phonon spectra of vicinal stepped surfaces of Cu(211) have been calcu lated using a molecular dynamics method combined with a semiempirical poten tial. The potential is based on an analytic form of inverse powers proposed by Finnis and Sinclair with the parametrization of Sutton and Chen. One of the four independent parameters of the potential was rescaled to reproduce the bulk phonon spectrum of Cu while retaining other properties of the bul k Cu close to the experimental values. Using this potential, we calculated the power surface phonon spectra, projection of the spectra at the high-sym metry points of surface Brillouin zone (SBZ), and the mean square displacem ents (MSD's) of atoms of the Cu(211) surface. The calculated projected phon on spectra at <(<Gamma>)over bar> and at two new SBZ points (at (X) over ba r and (Y) over bar) compare favorably with experiment and theory when avail able. The MSD of the Cu(211) surface is also well reproduced and its temper ature dependence shows that anharmonicity of the atomic motion becomes impo rtant above 200 K.