Accurate kinetic energy evaluation in electronic structure calculations with localised functions on real space grids

Chris-Kriton Skylaris, Arash A. Mostofi, Peter D. Haynes, Chris J. Pickard and Mike C. Payne

Theory of Condensed Matter, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, UK

We present a method for calculating the kinetic energy of localised functions represented on a regular real space grid. This method uses fast Fourier transforms applied to restricted regions commensurate with the simulation cell and is applicable to grids of any symmetry. In the limit of large systems it scales linearly with system size. Comparison with the finite difference approach shows that our method offers significant improvements in accuracy without loss of efficiency.

PACS numbers: 71.15.-m, 02.70.Bf, 02.70.Hm

Keywords: density functional theory, linear-scaling, kinetic energy, finite difference, FFT