二聚体水分子的10种稳定结构的MP2方法研究

Study on the ten stationary structures of water dimer by MP2 method

二聚体水体系是液态水分子体系中氢键存在的原型,目前对它的研究大多是关于其最稳定构型,而忽略了势能面上的其它稳定结构.本文在MP2/aug-cc-pVDZ理论水平下对二聚体水分子进行均衡(CP)校正梯度优化,计算得到二聚体水分子势能面上的10种稳定构型,并进一步计算得到了它们的相互作用能和偶极矩等重要性质.结果表明,具有Cs对称性的构型1最稳定,其相互作用能ΔE为-4.47 kcal/mol;而具有C2h对称性的构型8最不稳定,其相互作用能ΔE仅为-1.15 kcal/mol.

Water dimer is the archetype for aqueous hydrogen bonding, and investigations on it generally focused on the global minimum on the potential energy surface （PES）, but the rest stationary structures were ignored. In this paper, 10 stationary structures on the PES were obtained by the counterpoise corrected optimization at MP2/aug-cc-pVDZ level. The properties of these structures, such as binding energy and dipole moment, etc. were also calculated. Results show that the most stable structure is # 1 with C, symmetry and the corresponding interaction energy is --4.47 kcal/mol; while structure # 8 with a C2h symmetry is the most unstable, and the corresponding interaction energy is only --1.15 kcal/mol.