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arXiv 1901.09464physics.chem-phcond-mat.str-el
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三维过渡金属体系量子化学计算的高精度化:双原子分子的非线性场量子Monte Carlo与耦合团簇、密度泛函理论和实验的比较

On Achieving High Accuracy in Quantum Chemical Calculations of 3d Transition Metal Systems: A Comparison of Auxiliary-Field Quantum Monte Carlo with Coupled Cluster, Density Functional Theory, and Experiment for Diatomic Molecules

James Shee, Benjamin Rudshteyn, Evan J. Arthur, Shiwei Zhang, David R. Reichman, Richard A. Friesner

摘要:

采用无相位相干场量子Monte Carlo(ph-AFQMC)方法,利用相关采样技术计算了44个含过渡金属的3d双光子晶体的键离解能.我们研究了具有H,N,O,F,Cl和S配体的分子,包括由Truhlar及其同事首次编制的3dMLBE 20数据库中的分子,这些数据库中的计算值和实验值已被各个小组修订。为了直接比较我们的ph-AFQMC计算的准确性与先前发表的结果从10 DFT泛函,CCSD(T),和icMR-CCSD(T),我们建立了一个客观的选择协议,利用最新的实验结果,除了少数情况下,指定的差异。对于剩余的41个分子,我们发现ph-AFQMC与实验的一致性优于所有其他方法,平均绝对误差(MAE)为1.4(4)kcal/mol,最大误差为3(3)kcal/mol(括号说明了报告的实验不确定性和我们的ph-AFQMC计算的统计误差)。相比之下,CCSD(T)和B 97,这里考虑的性能最好的DFT泛函,MAE分别为2.8和3.7 kcal/mol,两种方法的最大误差超过17 kcal/mol。虽然需要更大和更多样化的数据集来证明ph-AFQMC确实是过渡金属体系的基准方法,但我们的结果表明,该方法具有巨大的潜力,与其他近似量子化学方法相比,表现出前所未有的一致性和准确性。

英文摘要:

The bond dissociation energies of a set of 44 3d transition metal-containing diatomics are computed with phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) utilizing a correlated sampling technique. We investigate molecules with H, N, O, F, Cl, and S ligands, including those in the 3dMLBE20 database first compiled by Truhlar and co-workers with calculated and experimental values that have since been revised by various groups. In order to make a direct comparison of the accuracy of our ph-AFQMC calculations with previously published results from 10 DFT functionals, CCSD(T), and icMR-CCSD(T), we establish an objective selection protocol which utilizes the most recent experimental results except for a few cases with well-specified discrepancies. With the remaining set of 41 molecules, we find that ph-AFQMC gives robust agreement with experiment superior to that of all other methods, with a mean absolute error (MAE) of 1.4(4) kcal/mol and maximum error of 3(3) kcal/mol (parenthesis account for reported experimental uncertainties and the statistical errors of our ph-AFQMC calculations). In comparison, CCSD(T) and B97, the best performing DFT functional considered here, have MAEs of 2.8 and 3.7 kcal/mol, respectively, and maximum errors in excess of 17 kcal/mol for both methods. While a larger and more diverse data set would be required to demonstrate that ph-AFQMC is truly a benchmark method for transition metal systems, our results indicate that the method has tremendous potential, exhibiting unprecedented consistency and accuracy compared to other approximate quantum chemical approaches.

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