Ab initiomolecular dynamics calculations with simple, localized, orthonormal real-space basis sets

Ab initio molecular dynamics, in which finite temperature molecular dynamics is performed with forces obtained from ``on the fly'' electronic structure calculations, is one of the most widely used theoretical tools for studying chemically active systems. Here, a significant step is taken to improve the efficiency, scaling with system size, and parallel efficiency of these calculations by the use of simple, localized, orthonormal real-space basis functions in conjunction with a unified reciprocal-space treatment of long-range interactions for various boundary conditions. This approach, which is capable of treating systems with zero-, one-, two-, or three-dimensional periodicity within a single framework, is shown to improve the convergence of total energies and forces by over an order of magnitude in grid size compared to the more commonly used plane-wave basis. Possibilities for employing the approach in a linear scaling method are briefly discussed.