Knizia Gerald, Adler Thomas B, Werner Hans-Joachim
Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
J Chem Phys. 2009 Feb 7;130(5):054104. doi: 10.1063/1.3054300.
The simple and efficient CCSD(T)-F12x approximations (x = a,b) we proposed in a recent communication [T. B. Adler, G. Knizia, and H.-J. Werner, J. Chem. Phys. 127, 221106 (2007)] are explained in more detail and extended to open-shell systems. Extensive benchmark calculations are presented, which demonstrate great improvements in basis set convergence for a wide variety of applications. These include reaction energies of both open- and closed-shell reactions, atomization energies, electron affinities, ionization potentials, equilibrium geometries, and harmonic vibrational frequencies. For all these quantities, results better than the AV5Z quality are obtained already with AVTZ basis sets, and usually AVDZ treatments reach at least the conventional AVQZ quality. For larger molecules, the additional cost for these improvements is only a few percent of the time for a standard CCSD(T) calculation. For the first time ever, total reaction energies with chemical accuracy are obtained using valence-double-zeta basis sets.
我们在最近的一篇通讯文章 [T. B. 阿德勒、G. 克尼齐亚和 H.-J. 维尔纳，《化学物理杂志》127, 221106 (2007)] 中提出的简单高效的CCSD(T)-F12x近似方法（x = a, b）将得到更详细的解释，并扩展到开壳层体系。文中给出了大量的基准计算，这些计算表明在各种应用中基组收敛性有了很大改进。这些应用包括开壳层和闭壳层反应的反应能、原子化能、电子亲和能、电离势、平衡几何结构和谐波振动频率。对于所有这些量，使用AVTZ基组已经能得到优于AV5Z质量的结果，并且通常AVDZ处理至少能达到传统AVQZ质量。对于更大的分子，这些改进的额外成本仅为标准CCSD(T)计算时间的百分之几。有史以来第一次，使用价层双ζ基组获得了具有化学精度的总反应能。
