论文标题
n $^5 $ - 尺度激发特异性的扰动理论
An N$^5$-scaling excited-state-specific perturbation theory
论文作者
论文摘要
我们表明，通过在类似于自然过渡轨道的基础上工作并使用改良的零秩序汉密尔顿，可以从系统大小中从第七阶降低到第五阶的最近引入的扰动校正的成本。 （被占用的）$^2 $（虚拟）$^3 $渐近缩放与地面二阶二阶Møller-plesset理论相匹配，但具有明显更高的预替代器，因为瓶颈是迭代的：它出现在基于Krylov-Subspace的基于Krylov-Spass的线性解决方案中，从而产生了第一阶波波功能。在这里，我们讨论了用于降低成本的修改后的零订单哈密顿式订单的详细信息，以及我们用于得出和验证不同条款的成本缩放的自动代码生成过程。总体而言，我们发现我们的修改对方法的准确性几乎没有影响，这与单打和双重运动耦合群集保持竞争力。
We show that by working in a basis similar to that of the natural transition orbitals and using a modified zeroth order Hamiltonian, the cost of a recently-introduced perturbative correction to excited state mean field theory can be reduced from seventh to fifth order in the system size. The (occupied)$^2$(virtual)$^3$ asymptotic scaling matches that of ground state second order Møller-Plesset theory, but with a significantly higher prefactor because the bottleneck is iterative: it appears in the Krylov-subspace-based solution of the linear equation that yields the first order wave function. Here we discuss the details of the modified zeroth order Hamiltonian we use to reduce the cost as well as the automatic code generation process we used to derive and verify the cost scaling of the different terms. Overall, we find that our modifications have little impact on the method's accuracy, which remains competitive with singles and doubles equation-of-motion coupled cluster.
