SURFACE VIBRATIONS OF AG(100) AND CU(100) - A MOLECULAR-DYNAMICS STUDY

We present molecular-dynamics studies of Ag(100) and Cu(100), using interatomic potentials obtained by the embedded-atom method. The low-temperature results for the surface phonon frequencies and polarizations at selected points in the two-dimensional Brillouin zone are in good agreement with experimental data and also with results of first-principles calculations on both systems. The mean-square vibrational amplitudes of the surface atoms are found to be isotropic and much larger than the reported values for the bulk. As a function of increasing temperature, the frequencies of the surface phonons are found to redshift and the peaks to broaden. The variation of the mean-square vibrational amplitude with temperature displays effects of enhanced surface anharmonicity.