Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel.
Phys Rev Lett. 2012 Nov 30;109(22):226405. doi: 10.1103/PhysRevLett.109.226405. Epub 2012 Nov 28.
We present a method for obtaining outer-valence quasiparticle excitation energies from a density-functional-theory-based calculation, with an accuracy that is comparable to that of many-body perturbation theory within the GW approximation. The approach uses a range-separated hybrid density functional, with an asymptotically exact and short-range fractional Fock exchange. The functional contains two parameters, the range separation and the short-range Fock fraction. Both are determined nonempirically, per system, on the basis of the satisfaction of exact physical constraints for the ionization potential and frontier-orbital many-electron self-interaction, respectively. The accuracy of the method is demonstrated on four important benchmark organic molecules: perylene, pentacene, 3,4,9,10-perylene-tetracarboxylic-dianydride (PTCDA), and 1,4,5,8-naphthalene-tetracarboxylic-dianhydride (NTCDA). We envision that for the outer-valence excitation spectra of finite systems the approach could provide an inexpensive alternative to GW, opening the door to the study of presently out of reach large-scale systems.
我们提出了一种从基于密度泛函理论的计算中获取外价准粒子激发能的方法，其精度可与 GW 近似范围内的许多体微扰理论相媲美。该方法使用了一种范围分离的混合密度泛函，其中包含渐近精确和短程分数 Fock 交换。该泛函包含两个参数，范围分离和短程 Fock 分数。这两个参数都是根据电离势和前沿轨道多电子自相互作用的精确物理约束，针对每个系统进行非经验确定的。该方法在四个重要的基准有机分子上进行了验证：苝、并五苯、3,4,9,10-苝四羧酸二酐（PTCDA）和 1,4,5,8-萘四羧酸二酐（NTCDA）。我们设想，对于有限体系的外价激发光谱，该方法可以提供一种比 GW 更经济的替代方法，为目前无法企及的大规模体系的研究开辟了道路。
