Basis set convergence of correlated calculations on He, H2, and He2
Basis set convergence of correlated calculations on He, H2, and He2
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DOI：
10.1063/1.481718
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发表时间：
2000-06
影响因子：
4.4
通讯作者：
Jae Shin Lee;S. Y. Park
中科院分区：
文献类型：
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作者：
Jae Shin Lee;S. Y. Park
研究了 He、H2 和 He2 的总能和相关能随着相关一致基组 cc-pVXZ 和 aug-cc-pVXZ(X=D,T,Q,5,6) 中基质量的增加而收敛的行为，以寻找合适的外推方案来预测 MP2、CCSD 和 CCSD(T) 级别的准确完整基组 (CBS) 极限。用于外推的函数形式是一个简单的多项式，包括相关一致基集中基数 X 的三次幂和高阶项以及指数函数。研究发现，使用 (X+k)−3 [对于 MP2，k=0，对于 CCSD 和 CCSD(T) 水平，k=−1] 对两个连续相关一致基组能量（总能量或相关能量）进行简单外推，通常给出对 CBS 极限能量最可靠（并且在总能量的情况下准确）的估计。它还表明，选择适当的基组，可以同样很好地表示片段和复合体中的电子运动......
The convergence behavior of the total and correlation energies of He, H2, and He2 with the increase of basis quality in the correlation-consistent basis sets, cc-pVXZ and aug-cc-pVXZ(X=D,T,Q,5,6), was studied to search for a proper extrapolation scheme to predict the accurate complete basis set (CBS) limits at the MP2, CCSD, and CCSD(T) level. The functional form employed for extrapolation is a simple polynomial including inverse cubic power and higher-order terms of the cardinal number X in the correlation-consistent basis set as well as exponential function. It is found that a simple extrapolation of two successive correlation-consistent basis set energies (total or correlation energies) using (X+k)−3 [k=0 for MP2 and k=−1 for CCSD and CCSD(T) level] gives in general the most reliable (and accurate in case of total energy) estimates to the CBS limit energies. It is also shown that the choice of proper basis set, which can represent the electronic motions in the fragment and complex equally well, appears...