(H_2O)_5环状异构体的氢键协同作用和相互作用能的多体效应

Cooperativity of hydrogen bonds and the contribution of many-body terms to the interaction energy in( H_2O)_5 ring water pentamers

在量子化学计算的基础上,采用一种简便的能量分解方案,讨论了(H2O)5四种环状异构体的稳定性、氢键协同作用、多体效应与水分子排布方式之间的关系。结果表明,虽然总相互作用能主要来自二体作用项的贡献,但异构体之间的稳定性的差异主要由三体作用项决定;环形结构中,以da-da-da方式形成的三联体,其三体作用会增加总的相互作用,从而增强环结构的稳定性;将此推广到六元环中,发现亦存在这种关系,因此da-da-da三联体的数目可作为环稳定性的直观判据。

Based on quantum chemistry calculations, this paper discusses the relationships between molecular ar- rangements, hydrogen bond cooperativity, many-body effects and the relative stability of （HE0）5 ring isomers after carrying out energy decomposition in a simple scheme. The results show that the total interaction energy mainly comes from two-body interactions, but three-body interactions may also make a major contribution to the relative stabilities of the isomers. When there is a donor-acceptor （da） triplet of the type da-da-da the ring can be stabi- lized by such three-body interactions. The relationship between the relative stability and number of da-da-da triplets can be confirmed in isomers of hexamers, and may be regarded as an intuitive way to evaluate the relative stabilities of ring water clusters.