水分子团簇分子间氢键协同作用

Cooperativity of the hydrogen bonds in water clusters

氢键是生物分子中重要的弱相互作用,对生命物质结构和功能的实现等方面有着重要的意义.在多分子聚集体中,氢键的强度会因周围环境或其他分子的改变而发生变化,即存在“协同作用”.氢键协同作用的研究对解释许多物理、化学、生物学现象也具有着重要意义.基于水分子中三体、四体相互作用对团簇稳定性具有较大贡献的事实,系统地构建了4种三元、四元水分子团簇结构(共计22000个),并在DLPNO-MP2/aug-cc-pVTZ水平上对氢键的协同作用的强弱进行了探讨.结果表明,分子间氢键的协同作用同时存在着短程的正协同和短程的负协同两种作用,其强度随分子间距离的增强快速衰减.这种协同作用与氢键相关原子电荷变化有关,本文的研究为进一步发展基于可极化力场的分子间协同作用计算方法提供依据.

Hydrogen bonding is an important weak interaction in biomolecules,which is of great significance to the realization of the structure and function of living substances.In molecular clusters,the strength of hydrogen bonds will change due to changes in the surrounding or other near-by molecules,which is known as the“cooperative effect”.The study of hydrogen bond cooperativity is also of great significance to explain many physical,chemical and biological phenomena.Based on the fact that the three-and four-body interactions between water molecules have a large contribution to the cluster stability,we systematically constructed four ternary or quaternary water molecules in equilibrium and non-equilibrium conformations.The cooperativity of hydrogen bonds was evaluated at the DLPNO-MP2/aug-cc-pVTZ level of theory.The results show that both short-range positive cooperative effect and short-range inverse cooperative effect is found in these clusters,and the cooperativity energy decays rapidly with the increase of intermolecular distance.This cooperative effect is also found related to the change of atomic charge related to hydrogen bonding.The research in this paper provides a basis for the further development of the calculation method of intermolecular cooperative effect.