A new DFT method for atoms and molecules in Cartesian grid

Abstract

Electronic structure calculation of atoms and molecules, in the past few decades has largely been dominated by density functional methods. This is primarily due to the fact that this can account for electron correlation effects in a rigorous, tractable manner keeping the computational cost at a manageable level. With recent advances in methodological development, algorithmic progress as well as computer technology, larger physical, chemical and biological systems are amenable to quantum mechanical calculations than ever before. Here we report the development of a new method for accurate reliable description of atoms, molecules within the Hohenberg-Kohn-Sham density functional theory (DFT). In a Cartesian grid, atom-centered localized basis set, electron density, molecular orbitals, two-body potentials are directly built on the grid. We employ a Fourier convolution method for classical Coulomb potentials by making an Ewald-type decomposition technique in terms of short- and long-range interactions. One-body matrix elements are obtained from standard recursion algorithms while two-body counterparts are done by direct numerical integration. A systematic analysis of our results obtained on various properties, such as component energy, total energy, ionization energy, potential energy curve, atomization energy, etc., clearly demonstrates that the method is capable of producing quite accurate and competitive (with those from other methods in the literature) results. In brief, a new variational DFT method is presented for atoms and molecules, \emph{completely} in Cartesian grid.