The Institute of Atomic and Molecular physics, Sichuan University, Chengdu, Sichuan 610065, China.
J Comput Chem. 2011 Oct;32(13):2896-901. doi: 10.1002/jcc.21872. Epub 2011 Jul 6.
This article investigates the errors in supermolecule calculations for the helium dimer. In a full CI calculation, there are two errors. One is the basis set superposition error (BSSE), the other is the basis set convergence error (BSCE). Both of the errors arise from the incompleteness of the basis set. These two errors make opposite contributions to the interaction energies. The BSCE is by far the largest error in the short range and larger than (but much closer to) BSSE around the Van der Waals minimum. Only at the long range, the BSSE becomes the larger error. The BSCE and BSSE largely cancel each other over the Van der Waals well. Accordingly, it may be recommended to not include the BSSE for the calculation of the potential energy curve from short distance till well beyond the Van der Waals minimum, but it may be recommended to include the BSSE correction if an accurate tail behavior is required. Only if the calculation has used a very large basis set, one can refrain from including the counterpoise correction in the full potential range. These results are based on full CI calculations with the aug-cc-pVXZ (X = D, T, Q, 5) basis sets.
本文研究了氦二聚体超分子计算中的误差。在完全组态相互作用（CI）计算中，存在两个误差。一个是基组叠加误差（BSSE），另一个是基组收敛误差（BSCE）。这两个误差都源于基组的不完整性。这两个误差对相互作用能有相反的贡献。BSCE 是迄今为止短程中最大的误差，并且比范德华最小值附近的 BSSE 更大（但更接近）。只有在长程中，BSSE 才成为较大的误差。BSCE 和 BSSE 在范德华阱中大部分相互抵消。因此，建议在从短距离到远超过范德华最小值的势能曲线计算中不包括 BSSE，但如果需要准确的尾部行为，则建议包括 BSSE 校正。只有在计算中使用了非常大的基组时，才可以在全势能范围内不包括对消校正。这些结果是基于 aug-cc-pVXZ（X = D、T、Q、5）基组的完全 CI 计算得出的。
