Further orbital-free kinetic-energy functionals for ab initio molecular dynamics

A recently introduced scheme for ab initio molecular-dynamics with an orbital-free density functional [Phys. Rev. B 49, 5220 (1994)] is extended so that the kinetic-energy functional guarantees correct results at third order of perturbation theory. The new density functional gives improved accuracy, yielding good agreement with well-converged Kohn-Sham results for many properties of metals such as aluminum. This molecular-dynamics scheme retains many of the advantages of the old: it is very fast, exhibits close to linear scaling with system size, and may be readily ''conditioned'' to maximize the molecular-dynamics time step.