Ab initio Hartree-Fock molecular dynamics with parallel processing: Application to small neutral and charged Li_n clusters

An ab initio molecular dynamics scheme based on a parallelized Hartree-Fock procedure is described. Analytical gradients of the Born-Oppenheimer ground state energy are used to compute the forces acting on atoms at each nuclear configuration along trajectories generated by solving classical equations of motion. Parallel processing of the two-electron integrals and gradients and optimization of the sequential parts of the self-consistent-field procedure allow for generation of trajectories that, for small systems, are long enough to provide for a meaningful dynamical analysis. The degree of detail and completeness of this analysis approaches that previously feasible only with semiempirical potentials. This is illustrated by application of the scheme to Li₆, Li₈, Li⁺₉ and Li₁₀ clusters.