Natural triple excitations in local coupled cluster calculations with pair natural orbitals
Natural triple excitations in local coupled cluster calculations with pair natural orbitals
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DOI：
10.1063/1.4821834
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发表时间：
2013-10-07
影响因子：
4.4
通讯作者：
Neese, Frank
中科院分区：
文献类型：
--
作者：
Riplinger, Christoph;Sandhoefer, Barbara;Neese, Frank
本文将先前发展的基于局部对自然轨道（DLPNO）的单双耦合簇（DLPNO- ccsd）方法扩展到微扰包含连通三重激励。该发展是基于三重自然轨道的概念，它跨越了计算给定三激发贡献的三个电子对的三对自然轨道（PNO）空间的联合空间。截断误差非常平滑，可以通过外推到零阈值来显着降低。然而，外推过程并不能提高相对能量。该方法的总体计算量与系统规模O(N)渐近线性。在烷烃链的试验计算中证实了实际的线性缩放。DLPNO-CCSD(T)近似相对于半规范CCSD（T-0）的精度与先前开发的DLPNO-CCSD方法相对于规范CCSD相当。对于具有挑战性的中等大小有机分子测试集，预测的相对能量平均误差约为0.5 kcal/mol。三元组校正通常会使总计算时间增加30%-50%。因此，可以在当前实现的基础上处理非常大的系统。除了线性C150H302（452个原子，bbb8800个基函数）外，我们还展示了整个蛋白质的CCSD(T)水平计算，Crambin具有644个原子，超过6400个基函数。(C) 2013 AIP出版有限责任公司
In this work, the extension of the previously developed domain based local pair-natural orbital (DLPNO) based singles-and doubles coupled cluster (DLPNO-CCSD) method to perturbatively include connected triple excitations is reported. The development is based on the concept of triples-natural orbitals that span the joint space of the three pair natural orbital (PNO) spaces of the three electron pairs that are involved in the calculation of a given triple-excitation contribution. The truncation error is very smooth and can be significantly reduced through extrapolation to the zero threshold. However, the extrapolation procedure does not improve relative energies. The overall computational effort of the method is asymptotically linear with the system size O(N). Actual linear scaling has been confirmed in test calculations on alkane chains. The accuracy of the DLPNO-CCSD(T) approximation relative to semicanonical CCSD(T-0) is comparable to the previously developed DLPNO-CCSD method relative to canonical CCSD. Relative energies are predicted with an average error of approximately 0.5 kcal/mol for a challenging test set of medium sized organic molecules. The triples correction typically adds 30%-50% to the overall computation time. Thus, very large systems can be treated on the basis of the current implementation. In addition to the linear C150H302 (452 atoms, >8800 basis functions) we demonstrate the first CCSD(T) level calculation on an entire protein, Crambin with 644 atoms, and more than 6400 basis functions. (C) 2013 AIP Publishing LLC.