Anharmonic vibrational analysis of water with traditional and explicitly correlated coupled cluster methods
Anharmonic vibrational analysis of water with traditional and explicitly correlated coupled cluster methods
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DOI：
10.1063/1.3464837
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发表时间：
2010-08-21
影响因子：
4.4
通讯作者：
Ten-no, Seiichiro
中科院分区：
文献类型：
--
作者：
Kahn, Kalju;Kirtman, Bernard;Ten-no, Seiichiro
众所周知，在传统的相关计算中，谐波频率相对于基组大小的收敛是缓慢的。我们现在报告说，在传统的CCSD（T）计算H2O与Dunning的cc-pVXZ系列基组的三次和四次力常数的收敛也令人沮丧的缓慢。作为替代方案，我们在CCSD（T）水平上探索基于R12的显式相关方法的性能。谐波频率和立方力常数的良好收敛性提供了这些明确相关的方法与R12适合的基础上，无论使用的标准近似和/或相关因子。然而，斯莱特型的geminal，优于线性r（12）的四次力常数和振动非谐常数。通过对CCSD（T）后效应的修正，从显式关联CCSD（T）计算得到的力常数成功地再现了具有光谱精度的水分子基频。(C)2010年美国物理学会。[doi：10.1063/1.3464837]
It is well known that the convergence of harmonic frequencies with respect to the basis set size in traditional correlated calculations is slow. We now report that the convergence of cubic and quartic force constants in traditional CCSD(T) calculations on H2O with Dunning's cc-pVXZ family of basis sets is also frustratingly slow. As an alternative, we explore the performance of R12-based explicitly correlated methods at the CCSD(T) level. Excellent convergence of harmonic frequencies and cubic force constants is provided by these explicitly correlated methods with R12-suited basis irrespective of the used standard approximation and/or the correlation factor. The Slater type geminal, however, outperforms the linear r(12) for quartic force constants and vibrational anharmonicity constants. The converged force constants from explicitly correlated CCSD(T) calculations succeed in reproducing the fundamental frequencies of water molecule with spectroscopic accuracy after corrections for post-CCSD(T) effects are made. (C) 2010 American Institute of Physics. [doi:10.1063/1.3464837]