Phillips Jordan J, Zgid Dominika
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
J Chem Phys. 2014 Jun 28;140(24):241101. doi: 10.1063/1.4884951.
We report an implementation of self-consistent Green's function many-body theory within a second-order approximation (GF2) for application with molecular systems. This is done by iterative solution of the Dyson equation expressed in matrix form in an atomic orbital basis, where the Green's function and self-energy are built on the imaginary frequency and imaginary time domain, respectively, and fast Fourier transform is used to efficiently transform these quantities as needed. We apply this method to several archetypical examples of strong correlation, such as a H32 finite lattice that displays a highly multireference electronic ground state even at equilibrium lattice spacing. In all cases, GF2 gives a physically meaningful description of the metal to insulator transition in these systems, without resorting to spin-symmetry breaking. Our results show that self-consistent Green's function many-body theory offers a viable route to describing strong correlations while remaining within a computationally tractable single-particle formalism.
我们报告了一种自洽格林函数多体理论在二阶近似（GF2）下的实现，用于分子系统。这是通过在原子轨道基中以矩阵形式表示的戴森方程的迭代解来完成的，其中格林函数和自能分别建立在虚频和虚时域上，并根据需要使用快速傅里叶变换来有效地变换这些量。我们将此方法应用于几个强关联的典型例子，例如即使在平衡晶格间距下也显示出高度多参考电子基态的H32有限晶格。在所有情况下，GF2都能对这些系统中的金属到绝缘体转变给出具有物理意义的描述，而无需诉诸自旋对称性破缺。我们的结果表明，自洽格林函数多体理论为描述强关联提供了一条可行的途径，同时仍处于计算上易于处理的单粒子形式体系内。
