The intermolecular potentials of the O2-O2 dimer: a detailed ab initio study of the energy splittings for the three lowest multiplet states.
The intermolecular potentials of the O2-O2 dimer: a detailed ab initio study of the energy splittings for the three lowest multiplet states.
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O2-O2 二聚体的分子间势：三个最低多重态能量分裂的详细从头算研究。
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
R. Hernández
中科院分区：
文献类型：
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作者：
M. Bartolomei;Marta I. Hernández;J. Campos;E. Carmona;R. Hernández
用高水平从头计算方法详细研究了O2(3Sigma)-O2(3Sigma)二聚体的三个最低多重态(单重态、三重态和五重态)的分子间势。使用的方法包括MRCI，ACPF，CASPT2，使用不同的活性空间和基组。五重态的计算结果与基准CCSD(T)计算结果进行了比较。正如预期的那样，尽管CASPT2方法比基于CI的方法性能更好，但以前的方法并不能准确地考虑色散相互作用。另一方面，研究表明，要准确地描述多重态之间的分裂，高关联方法是必要的。我们建议将CCSD(T)五重势与多组态单五重态和三重态五重态分裂相结合，分别得到单重态和三重态相互作用势。对于所采用的方法，计算的分裂是相当稳定的，除了矩形构型内的单重态和三重态的势垒区域，它对应于这些多重态的绝对最小值。然而，我们已经能够评估这一特定区域相互作用潜力的适当上下限。
Intermolecular potentials for the three lowest multiplet states (singlet, triplet and quintet) of the O2(3Sigma)-O2(3Sigma) dimer have been investigated in detail by means of high level ab initio calculations. The methods used include MRCI, ACPF, CASPT2, using different active spaces and basis sets. The results for the quintet state are compared with benchmark CCSD(T) calculations. As expected, the former methods do not account accurately for dispersion interactions, although the CASPT2 method performs better than the CI based ones. On the other hand, it is shown that highly correlated methods are necessary to accurately describe the splittings among the multiplet states. We propose to obtain singlet and triplet interaction potentials by combining CCSD(T) quintet potentials and multiconfigurational singlet-quintet and triplet-quintet splittings, respectively. The calculated splittings are quite stable regarding the method employed, except for the well region of the singlet and triplet states within the rectangular configuration, which corresponds to the absolute minima of these multiplet states. Nevertheless, we have been able to assess adequate upper and lower bounds to the interaction potential for this particular region.