Performance of a DFT code using Lagrange-sinc basis set for ground and excited state calculations: Exact exchange and Multiconfiguration effects

Abstract

Recently, we developed a self-consistent field program based on Kohn-Sham density functional theory using Lagrange functions, a family of localized real-space basis sets sharing certain attributes, as a the comparison with the results of Gaussian basis sets. The accuracy of the basis set in the atomization energies, ionization energies, electron affinities, and static polarizabilities of the Lagrange-sinc basis set with a scaling factor smaller than 0.22 Bohr was comparable to that of aug-cc-pV5Z. In particular, it showed high accuracy with rapid convergence in describing density or orbital changes by an external electric field, while Gaussian basis sets require a large set of diffuse functions to achieve the same accuracy. We also implemented a selfinteraction free method based on KLI approximation into the code and am extending it for excited state calculations as well as accurate ground state calculations by incorporating the multi-configurational nature of many-electron systems. In this talk, we present details of our method and numerical results for ground and excited state calculations.