Atomistic Computer Simulations of Melting, Diffusion and Thermal Defects in High Pressure Solids

Sammanfattning: The present work describes the use of atomistic computer simulations in the area of Condensed Matter Physics, and speci cally its application to the study of two problems: the dynamics of the melting phase transition and the properties of materials at extremely high pressures and temperatures, problems which defy experimental measurements and purely analytical calculations. A good sampling of techniques including classical and rst-principles Molecular Dynamics, and Metropolis Monte Carlo simulation have been applied in this study. It includes the calculation of melting curves for a wide range of pressures for elements such as Xe and H2, the comparison of two di erent models for molecular interactions in ZrO2 with respect to their ability to reproduce the melting point of the stable cubic phase, the study of the elastic constants of Fe at the extreme conditions of the Earth's inner core, and the stability of its crystalline phases. One of the most interesting results in this work is the characterization of di usion and defects formation in generic models of crystalline solids (namely Lennard-Jones and Embedded-atom) at the limit of superheating, including the role they play in the triggering of the melting process itself.