Kohn-Sham 動能密度在 meta-generalized gradient 近似中的角色

Abstract

In addition to the density ρ and its gradient ▽ρ, the meta-generalized gradient approximation (meta-GGA) functional depends on the Kohn-Sham kinetic energy density (KS KED) τ or the Laplacian of the density. In the present work, we study the importance of the KS KED relative to the meta-GGA functional. We replace the KS KED with some approximated KEDs and compare the performance of the original meta-GGA functional and the modified functionals. We choose the M05 functional and replace the KS KED with the approximated orbital free KEDs to generate a series of modified M05 type functionals. The result shows the full τ dependent functional (M05*) is superior to other modified M05 type functionals. The introduce of the KS kinetic energy density τ gives more accurate exchange-correlation functional.