Simulation of silicon clusters and surfaces via tight-binding molecular dynamics

A prescription is developed which incorporates the tight-binding total energy for silicon into the molecular-dynamics scheme of dynamical simulated annealing first proposed by Car and Parrinello [Phys. Rev. Lett. 55, 2471 (1985)]. The total-energy expression of Tom\'anek and Schl\"uter [Phys. Rev. Lett. 56, 1055 (1986); Phys. Rev. B 36, 1208 (1987)] with appropriate cutoff functions to permit molecular-dynamics simulations is used to calculate the forces on the ions and the electronic degrees of freedom. A self-contained description of the total-energy expression and the simulation method is presented. The scheme permits efficient quenching to zero-temperature and finite-temperature simulations of silicon clusters and surfaces. This method can perform realistic simulations on large systems of the order of hundreds of atoms with time requirements of the order of tens of Cray XMP/24 central-processing-unit hours. The prescription is tested and benchmarked on ground-state geometries of the Si₃ cluster and the reconstruction of the Si(100) surface.