An Atomistic Simulation Of Surface Dynamic Properties In Metals

In the present thesis, with the analytic embedded atom method (EAM), the surface dynamic properties, such as atomic vibrations, thermodynamic properties, anharmonicity and surface self-diffusion of typical metals are studied systematically, and compared with the experimental results.First, some basic concepts and general properties of surfaces are briefly summered. The analytic embedded atom method(EAM) and simulation methods, including surface lattice dynamics and molecular dynamics (MD) are introduced.In the third chapter, the surface vibration and thermodynamic properties of some typical surfaces for FCC and HCP metals are studied by means of the surface lattice dynamics and the analytic EAM. The calculated phonon frequencies and polarization of Ag(110) surface are in accord with experimental results. For Mg(0001) surface, the surface phonon dispersion and thermodynamic properties are calculated. The heat capacity and vibrational entropy, at a fixed temperature, decrease with increasing effective coordination. The phonon spectra of Cu vicinal surfaces are also investigated. With increasing terrace width, the relaxation persists for more layers, and the surface modes is more difficult to identify.In the fourth chapter, the surface anharmonicities are studied using MD. The temperature dependences of atomic interlayer distance, phonon frequencies, line-width, the mean square amplitude and the order parameter are calculated. The trend in the anharmonicity of Ag low-index surfaces varying with surface is obtained. The surface anharmonicity for BCC Fe is investigated. As the temperature increases, the Fe(111) surface disorders first, then the Fe(100) surface, and the thermal stability for Fe(110) surface is best, while the disorder for (110) surface is observed at a temperature, which is 300K below bulk melting temperature. For Ni(977) surface, the calculated layer structure factor indicates that the surface is well ordered and dose not permelt up to a temperature of 1700K, which is only 50K below bulk melting temperature in EAM. For Al(100) vicinal surfaces, the dependence of surface anharmonicity on terrace width is studied, and the result indicates that surface thermal stability increases with increasing terrace widths.In the fifth chapter, the self-diffusion behaviors of small two-dimensional atomic clusters on surface are studied with the MD simulations and the ana-...