The Role of Exact Exchange in the Description of Cu2+−(H2O)n (n = 1−6) Complexes by Means of DFT Methods

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• 作者：Raquel Rios-Font ; Mariona Sodupe ; Luis Rodrguez-Santiago ; Peter R. Taylor
• 刊名：Journal of Physical Chemistry A
• 出版年：2010
• 出版时间：October 14, 2010
• 年：2010
• 卷：114
• 期：40
• 页码：10857-10863
• 全文大小：288K
• 年卷期：v.114,no.40(October 14, 2010)
• ISSN：1520-5215

文摘

This paper analyses the behavior of different density functionals in the description of the most stable structures of Cu²⁺−(H₂O)_n complexes (n = 1−6). From n = 3 to n = 6, different coordination numbers of the metal cation were considered. The structures and energies of the complexes were theoretically determined by means of density functional methods that include different amounts of exact exchange: the BLYP functional (0% of exact exchange), the B3LYP functional (20% of exact exchange), the MPWB1K functional (44% of exact exchange), and BHLYP functional (50% of exact exchange). In addition, CCSD(T) calculations with a large basis set were carried out. It has been found that the functionals with lesser amount of exact exchange, especially BLYP, fail to describe the relative energies between the different structures of each cluster because these functionals tend to overestimate the stability of low-coordinated structures. The inclusion of the exact exchange into the functional improves the results, those obtained with MPWB1K and BHLYP being in very good agreement with the CCSD(T) ones. This behavior is related to the poor description of the second ionization energy of Cu by pure functionals, which leads to a too delocalized spin density in the complex with GGA functionals.