Approximating the basis set dependence of coupled cluster calculations: Evaluation of perturbation theory approximations for stable molecules
Approximating the basis set dependence of coupled cluster calculations: Evaluation of perturbation theory approximations for stable molecules
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DOI：
10.1063/1.1316041
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发表时间：
2000-11-08
影响因子：
4.4
通讯作者：
Peterson, KA
中科院分区：
文献类型：
--
作者：
Dunning, TH;Peterson, KA
耦合簇CCSD（T）方法提供了一个理论上合理的，准确的描述了广泛的分子的电子结构。然而，为了获得准确的结果，必须使用非常大的基组。由于CCSD（T）计算的计算成本形式上随着基函数数的七次方（N-7）而增加，因此CCSD（T）方法只能应用于有限范围的分子。在这项工作中，我们表明，CCSD（T）方法的基组依赖性很好地描述了微扰理论。从CCSD（T）/aug-cc-pVTZ计算开始，使用MP3方法模拟基组增加到aug-cc-pV 5 Z的影响，相对于完整的CCSD（T）/aug-cc-pV 5 Z计算，平均绝对误差小于+/-0.4 kcal/mol（D-e），+/-0.0002 A（r（e）），+/-2 cm（-1）（ω（e））、0.1 kcal/mol（IPe）和0.2 kcal/mol（EA（e））。虽然相应的MP2近似不能提供这种高水平的准确性，但它也应该对许多分子研究有用。当正确实现时，计算机时间的节省应该是显著的，因为MP3方法形式上可扩展为N-6，而MP2方法仅可扩展为N-5。(C)2000年美国物理学会。[S0021-9606（00）31942-0]。
The coupled cluster CCSD(T) method provides a theoretically sound, accurate description of the electronic structure of a wide range of molecules. To obtain accurate results, however, very large basis sets must be used. Since the computational cost of CCSD(T) calculations formally increases with the seventh power of the number of basis functions (N-7), the CCSD(T) method can only be applied to a restricted range of molecules. In this work we show that the basis set dependence of the CCSD(T) method is well described by perturbation theory. Starting with CCSD(T)/aug-cc-pVTZ calculations, use of the MP3 method to simulate the effect of increasing the basis set to aug-cc-pV5Z leads to average absolute errors, relative to the full CCSD(T)/aug-cc-pV5Z calculations, of less than +/-0.4 kcal/mol (D-e), +/-0.0002 A (r(e)), +/-2 cm(-1) (omega (e)), 0.1 kcal/mol (IPe), and 0.2 kcal/mol (EA(e)) for the test set of diatomic molecules considered here. Although the corresponding MP2 approximation does not provide this high level of accuracy, it also should be useful for many molecular studies. When properly implemented, the savings in computer time should be significant since the MP3 method formally scales as N-6, while the MP2 method scales as only N-5. (C) 2000 American Institute of Physics. [S0021-9606(00)31942-0].