Pittalis S, Kurth S, Sharma S, Gross E K U
Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
J Chem Phys. 2007 Sep 28;127(12):124103. doi: 10.1063/1.2777140.
Popular density functionals for the exchange-correlation energy typically fail to reproduce the degeneracy of different ground states of open-shell atoms. As a remedy, functionals which explicitly depend on the current density have been suggested. We present an analysis of this problem by investigating functionals that explicitly depend on the Kohn-Sham orbitals. Going beyond the exact-exchange approximation by adding correlation in the form of the Colle-Salvetti functional, we show how current-dependent terms enter the Colle-Salvetti expression and their relevance is evaluated. A very good description of the degeneracy of ground states for atoms of the first and second rows of the Periodic Table is obtained.
用于交换关联能的常用密度泛函通常无法重现开壳层原子不同基态的简并性。作为一种补救方法，有人提出了明确依赖于电流密度的泛函。我们通过研究明确依赖于Kohn-Sham轨道的泛函来对这个问题进行分析。通过以Colle-Salvetti泛函的形式添加关联来超越精确交换近似，我们展示了电流相关项如何进入Colle-Salvetti表达式并评估了它们的相关性。对于元素周期表第一和第二行原子的基态简并性，我们获得了非常好的描述。
