We present a molecular-dynamics analysis of the stable non-melting (100) and (111) surfaces of Al. An expansion of (111) surface and a contraction of (100) surface result from the calculations. At low temperature, the vertical mean-square vibrational amplitude is larger than the in-plane component, while at higher temperature the in-plane component approaches the vertical one. The evaluated linewidths and the energy shifts for the Rayleigh surface phonon are in good agreement with the He-surface scattering data. The effect of surface anharmonicity is much larger for the static properties than for the dynamical properties.--Presentazione poster by R Zivieri - Conferenza nazionale