Explicitly correlated Wn theory: W1-F12 and W2-F12
Explicitly correlated Wn theory: W1-F12 and W2-F12
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DOI：
10.1063/1.3697678
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发表时间：
2012-03-28
影响因子：
4.4
通讯作者：
Martin, Jan M. L.
中科院分区：
文献类型：
--
作者：
Karton, Amir;Martin, Jan M. L.
为了扩展W1和W2从头计算热化学方法的适用性，我们提出了明确相关的版本，表示为W1-F12和W2-F12。在W2-F12中，我们可以“保存”一个基数（即，角动量），而不会损失精度;在W1-F12中，我们可以对第一行化合物这样做，但不能对第二行化合物这样做。在W 4 -11基准数据集中第一行分子的均方根偏差（RMSD）= 0.19 kcal/mol时，W1-F12实际上上级于普通的W1理论。对于整个W 4 -11组，W2-F12产生RMSD = 0.20 kcal/mol，与普通W2理论的0.19 kcal/mol相当。W1-F12和W2-F12的扩展适用范围不仅是由于较低的计算成本，而且还大大减少了内存，特别是存储需求。它们通过应用于核酸和聚并苯来说明（最多四个环），其气相生成热修正如下：Δ H-f度（298）= 19.6（苯），34.94（萘）、53.9、（蒽）、73.9（并四苯/并四苯）、54.9（腺嘌呤）、-16.3（胞嘧啶）、5.1（鸟嘌呤）、-80.6（胸腺嘧啶）和-71.6（尿嘧啶）kcal/mol。我们对DNA/RNA碱基的理论值在很大程度上证实了最近基于低得多的计算的预测。苯、萘和蒽的W_1-F_12理论值与实验值符合得很好。然而，W1-F12和其他计算估计表明，并四苯的公认实验值不能与较低并苯的实验值相一致：我们建议Δ H-f度（298）[并四苯（g）] = 74.25 +/- 1 kcal/mol是一个更现实的估计。(C)2012年美国物理学会。[http：//dx.doi.org/10.1063/1.3697678]
In an attempt to extend the applicability of the W1 and W2 ab initio computational thermochemistry methods, we propose explicitly correlated versions thereof, denoted W1-F12 and W2-F12. In W2-F12, we can "save" one cardinal number (viz., angular momentum) in the basis set sequences without loss in accuracy; in W1-F12, we can do so for first-row compounds but not for second-row compounds. At a root mean square deviation (RMSD) = 0.19 kcal/mol for the first-row molecules in the W4-11 benchmark dataset, W1-F12 is in fact superior to ordinary W1 theory. For the entire W4-11 set, W2-F12 yields a RMSD = 0.20 kcal/mol, comparable to 0.19 kcal/mol from ordinary W2 theory. The extended applicability ranges of W1-F12 and W2-F12 are not just due to the lower computational cost but also to greatly reduced memory and especially storage requirements. They are illustrated through applications to nucleic acids and to polyacenes (with up to four rings), for which the following revised gas-phase heats of formation are found: Delta H-f degrees(298) = 19.6 (benzene), 34.94 (naphthalene), 53.9, (anthracene), 73.9 (naphthacene/tetracene), 54.9 (adenine), -16.3 (cytosine), 5.1 (guanine), -80.6 (thymine), and -71.6 (uracil) kcal/mol. Our theoretical values for the DNA/RNA bases largely confirm recent predictions based on much lower-level calculations. The W1-F12 theoretical values for benzene, naphthalene, and anthracene are in very good to reasonable agreement with experiment. However, both W1-F12 and other computational estimates show that the accepted experimental value for naphthacene cannot be reconciled with those for the lower acenes: we suggest that Delta H-f degrees(298) [naphthacene(g)] = 74.25 +/- 1 kcal/mol is a more realistic estimate. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697678]