Computer simulations of H atoms adsorbed on BCC(110) metals

Anharmonicity in surface potential wells can play a large role in the structure, the dynamics, and the thermodynamic properties of the surface system. We present three studies in which we examine the effects of a highly anharmonic surface potential well on a system of H atoms on a (110) surface of a BCC Metal.; The first study is a look at single H atom dynamics. We characterize different types of trajectories, look at the effects of trajectories at different energies, and finally create an ensemble of non-interacting particles of which we examine the power spectra. We show that the power spectra of {dollar}psb{lcub}x{rcub}{dollar} and that of {dollar}psb{lcub}y{rcub},{dollar} exhibit strikingly different behavior, and that the spectra of {dollar}psb{lcub}y{rcub}{dollar} is a broad band spectrum as has been seen in experimental systems.; The second study is an extension of the first, in that we added interactions between the hydrogen atoms. For a 20 x 20 surface of atoms, we show spontaneous symmetry breaking for the surface and short range order in the y direction only. The anharmonicity of the well plays a key role at lower temperatures. We also examine the dynamic structure factors for two characteristic temperatures, and discuss the liquid-like nature of the system. Finally, we comment briefly on the diffusivity of the H atoms on the surface, and make the argument that the diffusion of this system is highly correlated.; The third study calculates the surface entropy vs. coverage plot for a surface system with a highly anharmonic and also a moderately anharmonic surface potential well. We show that the vibrational surface entropy is a major component in the total surface entropy. We finally compare our results to the results for H/W(110).