The ΔNO method for static correlation is combined with second-order Møller-Plesset perturbation theory (MP2) and coupled-cluster singles and doubles (CCSD) to account for dynamic correlation. The MP2 and CCSD expressions are adapted from finite-temperature CCSD, which includes orbital occupancies and vacancies, and expanded orbital summations. Correlation is partitioned with the aid of damping factors incorporated into the MP2 and CCSD residual equations. Potential energy curves for a selection of diatomics are in good agreement with extrapolated full configuration interaction results and on par with conventional multireference approaches.

中文翻译：

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使用ΔNO-MP2和ΔNO-CCSD捕获静态和动态相关性。

静态关联的ΔNO方法与二阶Møller-Plesset微扰理论（MP2）和耦合集群单双打（CCSD）相结合，以解决动态关联问题。MP2和CCSD表达式改编自有限温度CCSD，其中包括轨道占用和空位，以及扩展的轨道总和。借助纳入MP2和CCSD残余方程的阻尼因子，可以对相关性进行划分。选择双原子的势能曲线与外推的全构型相互作用结果非常吻合，与传统的多参考方法相当。