Improved Cluster-in-Molecule Local Correlation Approach for Electron Correlation Calculation of Large Systems
Improved Cluster-in-Molecule Local Correlation Approach for Electron Correlation Calculation of Large Systems
复制标题
用于大型系统电子相关计算的改进分子内簇局部相关方法
DOI：
10.1021/jp501976x
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发表时间：
2014
影响因子：
2.9
通讯作者：
Li Shuhua
中科院分区：
文献类型：
--
作者：
Guo Yang;Li Wei;Li Shuhua
提出了一种改进的分子团簇（CIM）局域关联方法，使大体系的电子关联计算更准确、更快速。我们提出了一种改进的策略，构建虚拟LMO的各种集群，这是适用于各种类型的基集。为了恢复中程电子相关性，这是重要的定量描述的大型系统，我们发现，一个更大的距离阈值（）是必要的高精度的结果。计算结果表明，采用适当的微扰系数，CIM-MP2（second-order Møller-Plesser perturbation theory，MP2）或CIM-CCSD（coupled cluster singles and doubles，CCSD）方法在不同的基组下，对大范围的体系都能恢复99.8%以上的关联能.此外，本发明的CIM-MP2方案可以提供可靠的相对能量差作为传统的MP2方法的多肽的二级结构。
An improved cluster-in-molecule (CIM) local correlation approach is developed to allow electron correlation calculations of large systems more accurate and faster. We have proposed a refined strategy of constructing virtual LMOs of various clusters, which is suitable for basis sets of various types. To recover medium-range electron correlation, which is important for quantitative descriptions of large systems, we find that a larger distance threshold (ξ) is necessary for highly accurate results. Our illustrative calculations show that the present CIM-MP2 (second-order Møller-Plesser perturbation theory, MP2) or CIM-CCSD (coupled cluster singles and doubles, CCSD) scheme with a suitable ξ value is capable of recovering more than 99.8% correlation energies for a wide range of systems at different basis sets. Furthermore, the present CIM-MP2 scheme can provide reliable relative energy differences as the conventional MP2 method for secondary structures of polypeptides.