由非迭代修正补充的降秩形式论得到的近精确CCSDT能量学
Near-exact CCSDT energetics from rank-reduced formalism supplemented by non-iterative corrections
摘要：
我们引入了一个非迭代的能量校正，添加到顶部的秩减少耦合集群方法与单，双，和三重取代，占从父三重激发子空间排除的激发。修正公式是通过采用耦合簇拉格朗日形式主义与一个额外的假设，即父激发子空间是封闭的Fock算子的作用下，推导出来的。由于三重激励振幅张量的秩降形式，评估校正的计算成本为$N^7$与系统大小$N$成比例。所提出的方法的准确性和计算效率进行评估的总相关能量和相对相关能量。我们表明，非迭代校正可以实现两个单独的角色。如果kJ/mol的分数的精度水平对于给定系统是足够的，则校正显著地降低了计算的迭代部分中所需的母三重激发子空间的维度。同时，它能够再现准确的CCSDT结果的精度水平低于0.1 kJ/mol，具有较大的，但仍然合理的，父激发子空间的尺寸。这通常可以以仅比CCSD（T）方法所需的计算成本大几倍的计算成本来实现。所提出的方法保留了黑箱功能的单参考耦合集群理论的父激发子空间的尺寸仍然是唯一的额外的参数，必须指定。
英文摘要：
We introduce a non-iterative energy correction, added on top of the rank-reduced coupled-cluster method with single, double, and triple substitutions, that accounts for excitations excluded from the parent triple excitation subspace. The formula for the correction is derived by employing the coupled-cluster Lagrangian formalism with an additional assumption that the parent excitation subspace is closed under the action of the Fock operator. Owning to the rank-reduced form of the triple excitation amplitudes tensor, the computational cost of evaluating the correction scales as $N^7$ with the system size, $N$. The accuracy and computational efficiency of the proposed method is assessed both for total and relative correlation energies. We show that the non-iterative correction can fulfill two separate roles. If an accuracy level of a fraction of kJ/mol is sufficient for a given system the correction significantly reduces the dimension of the parent triple excitation subspace needed in the iterative part of the calculations. Simultaneously, it enables to reproduce the exact CCSDT results to an accuracy level below 0.1 kJ/mol with a larger, yet still reasonable, dimension of the parent excitation subspace. This typically can be achieved at a computational cost only several times larger than required for the CCSD(T) method. The proposed method retains black-box features of the single-reference coupled-cluster theory; the dimension of the parent excitation subspace remains the only additional parameter that has to be specified.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
