Explicitly correlated coupled cluster method for accurate treatment of open-shell molecules with hundreds of atoms
Explicitly correlated coupled cluster method for accurate treatment of open-shell molecules with hundreds of atoms
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DOI：
10.1063/5.0012753
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发表时间：
2020-09-07
影响因子：
4.4
通讯作者：
Valeev, Edward F.
中科院分区：
文献类型：
--
作者：
Kumar, Ashutosh;Neese, Frank;Valeev, Edward F.
利用微扰三重态方法[CCSD（T）（（F12）over bar）]，我们给出了开壳层物种高自旋态显关联耦合团簇单、双态的近线性标度表达式.该方法基于传统的开壳CCSD形式[M. Saitow等人，J. Chem.Phys.146，164105（2017）]，利用域局部对自然轨道（DLPNO）框架。使用自旋独立的成对自然轨道集确保与先前报道的闭壳层形式主义完全一致，对成本只有轻微的影响（例如，对于C160 H322正烷烃，开壳层形式仅比闭壳层对应物慢1.5倍，测量的尺寸复杂性约为1.2）。在一台多核计算机上，在不到3天的时间内，对具有超过550个原子和5000个基函数的开壳层系统的完全基集（CBS）极限附近的耦合团簇能量进行评估是可行的。aug-cc-pVTZ DLPNO-CCSD（T）（（F12）over bar）对348个核心燃烧物质基准组中50个最大分子的生成热的贡献[J. Klippenstein等人，J. Phys. Chem. A 121，6580-6602（2017）]与外推CBS CCSD（T）参考值的均方根偏差（RMSD）为0.3 kcal/mol。对于一组更具挑战性的50个反应，涉及小的封闭和开放壳层分子[G。Knizia等人，J. Chem. Phys. 130，054104（2009）]，aug-cc-pVQ（+d）Z DLPNO-CCSD（T）（（F12）对棒）产生了与CBS CCSD（T）估计值相似的0.4 kcal/mol的RMSD。由AIP Publishing授权出版。
We present a near-linear scaling formulation of the explicitly correlated coupled-cluster singles and doubles with the perturbative triples method [CCSD(T)((F12) over bar)] for high-spin states of open-shell species. The approach is based on the conventional open-shell CCSD formalism [M. Saitow et al., J. Chem. Phys. 146, 164105 (2017)] utilizing the domain local pair-natural orbitals (DLPNO) framework. The use of spinindependent set of pair-natural orbitals ensures exact agreement with the closed-shell formalism reported previously, with only marginally impact on the cost (e.g., the open-shell formalism is only 1.5 times slower than the closed-shell counterpart for the C160H322 n-alkane, with the measured size complexity of approximate to 1.2). Evaluation of coupled-cluster energies near the complete-basis-set (CBS) limit for open-shell systems with more than 550 atoms and 5000 basis functions is feasible on a single multi-core computer in less than 3 days. The aug-cc-pVTZ DLPNO-CCSD(T)((F12) over bar) contribution to the heat of formation for the 50 largest molecules among the 348 core combustion species benchmark set [J. Klippenstein et al., J. Phys. Chem. A 121, 6580-6602 (2017)] had root-mean-square deviation (RMSD) from the extrapolated CBS CCSD(T) reference values of 0.3 kcal/mol. For a more challenging set of 50 reactions involving small closed- and open-shell molecules [G. Knizia et al., J. Chem. Phys. 130, 054104 (2009)], the aug-cc-pVQ(+d)Z DLPNO-CCSD(T)((F12) over bar) yielded a RMSD of similar to 0.4 kcal/mol with respect to the CBS CCSD(T) estimate. Published under license by AIP Publishing.