In molecular dynamics and Monte Carlo simulations, the energy of a many-body system must be computed repeatedly for millions of configurations. It is therefore essential to use theories and algorithms that allow for fast calculations. In quantum chemistry, the extended Huckel method is one of the most economic theoretical approaches for calculating energies. Although simple, this method gives sufficiently accurate results in appropriately selected applications. A combination of molecular dynamics and Monte Carlo simulations with the extended Huckel method should therefore be useful in studying dynamic phenomena near surfaces and in the solid state. The proposed research will study the reconstruction of the Si(111) ( 3 x 3) R30 -B surface structure using the extended Huckel method and Monte Carlo simulation. Density functional theory is ideal for extended systems and large molecules. Although computationally intensive, it tends to give excellent results especially for free-electron systems. Central in this theory is that the ground state energy is a unique functional of the electron density. There is no need for any iteration in density functional calculations. The second focus of the research will be to continue explorations of the combination of density functional theory and computer simulation to study dynamic processes in condensed phase systems.
