CH_3Cl分子间相互作用的理论研究

Theoretical Study on the Intermolecular Interaction of CH_3Cl

在MP2/6-311++G(3d,3p)电子相关校正水平上,对CH3C l二聚体可能存在的几何构型进行全自由度能量梯度优化,发现有三种势能面上极小点的构型。进一步在高级电子相关校正的MP4SDTQ、CCSD(T)/6-311++G(3df,3pd)方法水平上,对其中具有平面环状C2h对称性的总能量最小的构型进行精确计算,得到CH3C l二聚体的结合能为-8.764KJ/mol。能量分解表明在分子间相互作用中色散与静电相互作用相近,色散与静电作用能分别占总吸引能的41.8%和38.1%。分析了二聚体的谐振频率,并进行了频率归属。

Various possible structures of the CH3Cl dimer have been optimized at the MP2/6-311＋＋ G（3d,3p） electron correction level, three minimum geometies have been found on the potential energy surface. At high order electron correction MP4SDTQ and CCSD （T）/6-311 ＋ ＋ G（3df, 3pd） level, the binding energy of the most stable structure which is planar cyclic C2h symmetry of the CH3Cl dimer has been calculated and the binding energy △ECCSD（T）^CP is -8.764 KJ/mol. The results of energy decomposition show that the dispersion interaction is close to the electrostatic interaction. The dispersion energy and electrostatic energy relative to the total attractive energy accounting for 41.8% and 38.1% , respectively. The harmonic vibrational frequencies of three minimum geometies have been analyzed and assigned at MP2/6-311＋ ＋G（3d,3p） level.