Fabiano E, Della Sala F
National Nanotechnology Laboratory of INFM-CNR, Distretto Tecnologico, Università del Salento, Via per Arnesano, I-73100 Lecce, Italy.
J Chem Phys. 2007 Jun 7;126(21):214102. doi: 10.1063/1.2735300.
A local Kohn-Sham (KS) exchange-correlation potential is derived by localizing the second-order self-energy operator, using approximations to the linear response Sham-Schlüter equation. Thanks to the use of the resolution-of-identity technique for the calculation of the self-energy matrix elements, the method is very efficient and can be applied to large systems. The authors investigate the KS energy gaps and lowest excitation energies of atoms and small- and medium-size molecules. Reference KS energy gaps (from accurate densities) of atoms and small molecules can be reproduced with great accuracy. For larger systems they found that the KS energy gap is smaller than the one obtained from the local-density approximation, showing the importance of an ab initio correlation in the Kohn-Sham potential.
通过对二阶自能算符进行局域化，并利用线性响应沙姆 - 施吕特方程的近似，推导出了局域的科恩 - 沙姆（KS）交换关联势。由于在计算自能矩阵元时使用了单位分解技术，该方法非常高效，可应用于大型系统。作者研究了原子以及中小分子的KS能隙和最低激发能。原子和小分子的参考KS能隙（来自精确密度）能够被高精度地重现。对于更大的系统，他们发现KS能隙比从局域密度近似得到的能隙更小，这表明在科恩 - 沙姆势中从头算关联的重要性。
