标题： 关于运动方程耦合簇理论与GW近似的联系 显示英文标题

标题： On The Relation Between Equation-of-Motion Coupled-Cluster Theory and the GW Approximation

摘要： 我们讨论了电离势（IP）和电子亲和力（EA）方程组耦合簇（EOM-CC）理论的解析和图解结构，目的是使其与流行的$GW$近似方法处于同等地位。对于时序单粒子格林函数来说，这种比较最为直接，我们表明，由单双激发（EOM-CCSD）计算得到的格林函数在高阶时包含比$GW$近似更少的环图，这是由于前者在时序处理上的不平衡所致。然而，EOM-CCSD 格林函数包含了大量顶点修正，包括梯子图、混合环-梯子图和交换图。通过包含三重激发，EOM-CCSDT 格林函数包含了$GW$近似中所有的图以及许多高阶顶点修正。同样用这种语言，我们讨论了 EOM-CCSD 方程的一些常见近似，其中许多可以归类为图的消去。最后，我们通过计算所谓的$GW$100 测试集 [J. Chem. Theory Comput. 2015, 11, 5665-5687] 中所含分子的主要带电激发能，给出了数值结果。我们认为，在分子中交换与屏蔽一样重要，提倡使用哈特里-福克参考态和自能中的二阶交换。 显示英文摘要

摘要： We discuss the analytic and diagrammatic structure of ionization potential (IP) and electron affinity (EA) equation-of-motion coupled-cluster (EOM-CC) theory, in order to put it on equal footing with the prevalent $GW$ approximation. The comparison is most straightforward for the time-ordered one-particle Green's function, and we show that the Green's function calculated by EOM-CC with single and double excitations (EOM-CCSD) includes fewer ring diagrams at higher order than does the $GW$ approximation, due to the former's unbalanced treatment of time-ordering. However, the EOM-CCSD Green's function contains a large number of vertex corrections, including ladder diagrams, mixed ring-ladder diagrams, and exchange diagrams. By including triple excitations, the EOM-CCSDT Green's function includes all diagrams contained in the $GW$ approximation, along with many high-order vertex corrections. In the same language, we discuss a number of common approximations to the EOM-CCSD equations, many of which can be classified as elimination of diagrams. Finally, we present numerical results by calculating the principal charged excitations energies of the molecules contained in the so-called $GW$100 test set [J. Chem. Theory Comput. 2015, 11, 5665-5687]. We argue that (in molecules) exchange is as important as screening, advocating for a Hartree-Fock reference and second-order exchange in the self-energy.