Past Event: Oden Institute Seminar

Towards the optimal basis set in the Kohn-Sham density functional theory

Lin Lin, Lawrence Berkeley National Lab

Abstract

Kohn-Sham density functional theory (KSDFT) is by far the most widely used electronic structure theory for condensed matter systems. However, the discretization cost, i.e. the number of basis functions to discretize the Kohn-Sham Hamiltonian operator is generally large, which is an important factor that hinders the application of KSDFT to systems of large size. Recently we have developed two techniques to reduce the discretization cost effectively and systematically. In the first part of the talk, we propose the adaptive local basis functions, which achieve high accuracy in the total energy calculation with a small number of basis functions. The adaptive local basis functions are strictly localized in the real space, and the Kohn-Sham orbitals are reconstructed from the adaptive local basis functions under the discontinuous Galerkin (DG) framework. In the second part of the talk, we propose the optimized local basis functions which further improve the adaptive local basis functions, and can be used for the force calculation with application to structure optimization and molecular dynamics. We show that using the optimized local basis functions, the atomic force can be accurately evaluated by the Hellman-Feynman force with systematically controlled Pulay force. (Joint work with Weinan E, Jianfeng Lu and Lexing Ying)