Generalized Energy-Based Fragmentation CCSD(T)-F12a Method and Application to the Relative Energies of Water Clusters (H2O)20
Generalized Energy-Based Fragmentation CCSD(T)-F12a Method and Application to the Relative Energies of Water Clusters (H2O)20
复制标题
广义能量碎裂 CCSD(T)-F12a 方法及其在水团簇 (H2O)20 相对能量中的应用
DOI：
10.1021/ct401060m
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发表时间：
2014
影响因子：
5.5
通讯作者：
Shuhua Li
中科院分区：
文献类型：
--
作者：
Kedong Wang;Wei Li;Shuhua Li
针对大中型系统耦合簇的显相关F12a与非迭代三元修正[CCSD(T)-F12a]方法，实现了广义能量碎片化（GEBF）方法。通过结合正则hartret - fock （HF）总能量和GEBF-X相关能，证明GEBF-X/HF方法比原始GEBF-X方法更精确，其中X可以是任何电子相关方法，如二阶m - ller - plesset微动理论（MP2）， MP2- f12， CCSD(T)和CCSD(T)-F12a。通过结合MP2-F12和CCSD(T)-F12a电平的GEBF-X/HF结果，我们可以近似地达到CCSD(T)完全基集（CBS）极限。我们对10个20-mers水的低能异构体的测试计算表明，对于大型水团簇的相对能量，既要考虑基集效应，也要考虑高能级电子相关效应，其中前者更为重要。此外，还利用CBS极限下的GEBF-CCSD(T)/HF方法对密度泛函理论（DFT）方法的32个层次进行了评价。结果表明，DFT方法难以预测20-mers水的同分异构体之间的相对能。在CBS极限下的GEBF-CCSD(T)/HF方法有望成为DFT和其他复杂结构中大型系统的电子相关方法的基准，在这些方法中，基集和电子相关效应都很重要。
The generalized energy-based fragmentation (GEBF) approach has been implemented for the explicitly correlated F12a of coupled-cluster with the noniterative triples corrections [CCSD(T)-F12a] method for medium- and large-sized systems. By combining the canonical Hartree–Fock (HF) total energies and the GEBF-X correlation energies, the GEBF-X/HF method is illustrated to be more accurate than the origin GEBF-X method, where X could be any electron correlation method, such as second-order Møller–Plesset perturbation theory (MP2), MP2-F12, CCSD(T), and CCSD(T)-F12a. By combining the GEBF-X/HF results at the MP2-F12 and CCSD(T)-F12a levels, we can approximately achieve the CCSD(T) complete basis set (CBS) limit. Our test calculations for 10 low-energy isomers of water 20-mers show that for the relative energies of large water clusters, both the basis set and high-level electron correlation effects should be taken into account, in which the former is even more important. In addition, the GEBF-CCSD(T)/HF method at the CBS limit is used to evaluate 32 levels of density functional theory (DFT) methods. The results show that the DFT methods are difficult to predict the relative energies between the isomers of water 20-mers. The GEBF-CCSD(T)/HF method at the CBS limit is expected to be a benchmark for DFT and other electron correlation methods for medium- and large-sized systems with complex structures, in which both the basis set and electron correlation effects are important.