论文标题

通过利用动态层次结构来优化耦合群集振幅的协同方法

A Synergistic Approach towards Optimization of Coupled Cluster Amplitudes by Exploiting Dynamical Hierarchy

论文作者

Patra, Chayan, Agarawal, Valay, Halder, Dipanjali, Chakraborty, Anish, Mondal, Dibyendu, Halder, Sonaldeep, Maitra, Rahul

论文摘要

确定簇幅度的耦合群集迭代方案涉及一组非线耦合差方程。在振幅跨越的空间中,将方程组的集合分析为一个多变量时间二散图,其中时间概念以隐式出现。通过观察到簇幅度在其幅度的分布方面的弛豫时间尺度上有差异,耦合的群集迭代动力学被认为是共存缓慢,快速放松模式的协同运动,表现出一种动力学等级结构。通过鉴定高度阻尼的辅助幅度,与主幅度相比,它们的时间变化可以忽略,这些振幅需要更长的时间才能达到固定点。我们通过分析建立绝热近似,其中这些辅助幅度中的每一个表示为集体主振幅的独特参数函数,从而使我们能够以后者为独立的自由度来研究优化。这种振幅的解耦可显着降低计算缩放,而无需牺牲基态能量的准确性,如许多具有挑战性的分子应用所证明的那样。还讨论了治疗高阶后效应后效应的路线图。

The coupled cluster iteration scheme for determining the cluster amplitudes involves a set of nonlinearly coupled difference equations. In the space spanned by the amplitudes, the set of equations are analysed as a multivariate time-discrete map where the concept of time appears in an implicit manner. With the observation that the cluster amplitudes have difference in their relaxation timescales with respect to the distributions of their magnitudes, the coupled cluster iteration dynamics are considered as a synergistic motion of coexisting slow and fast relaxing modes, manifesting a dynamical hierarchical structure. With the identification of the highly damped auxiliary amplitudes, their time variation can be neglected compared to the principal amplitudes which take much longer time to reach the fixed points. We analytically establish the adiabatic approximation where each of these auxiliary amplitudes are expressed as unique parametric functions of the collective principal amplitudes, allowing us to study the optimization with the latter taken as the independent degrees of freedom. Such decoupling of the amplitudes significantly reduces the computational scaling without sacrificing the accuracy in the ground state energy as demonstrated by a number of challenging molecular applications. A road-map to treat higher order post-adiabatic effects is also discussed.

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