三氯乙酸二聚体的量子化学研究  

Theoretical investigation on the interaction of 2,2,2-Trichloroacetic acid dimer

作　　者：李会学[1] 潘素娟[2] 萧泰[2] 耿志远[2] 

机构地区：[1]天水师范学院生化学院,天水741000 [2]西北师范大学化学化工学院,兰州730070

出　　处：《四川大学学报（自然科学版）》2008年第5期1207-1213,共7页Journal of Sichuan University(Natural Science Edition)

基　　金：天水师范学院科研基金(TSB0503)

摘　　要：用密度泛函理论B3LYP方法选取6—311＋＋G（d，P）基组对三氯乙酸-三氯乙酸复合物进行了量子化学计算研究，通过在相同水平下的频率振动分析发现了该势能面上5个极小值点，其最稳定构型对应一强O…H-O型氢键，其结合能在消除基组重叠误差后为-68．03kJ·mol^-1．通过自然键轨道（NBO）分析，研究了电荷转移及轨道相互作用．通过自洽反应场（SCRF）理论中的极化连续模型（PCM）在介电常数分别为1．0，2．247，4．9，7．58。10．36，20．7，38．2，46．7，78．39的不同溶剂环境下重新优化最稳定构型A，研究了溶剂对三氯乙酸二聚体几何构型及结合能的影响．发现溶剂化作用增大了三氯乙酸分子间的结合能，导致O…H距离减小，当溶液介电常数在1．0～20．7范围时，溶剂效应十分显著，当介电常数大于38．2后，溶剂化作用几乎达到了极限．Trichloroacetic acid dimer was subjected to density functional theory calculations using 6-311 ＋ ＋ G （d, p） basis set. Five equilibrium isomers were located on the potential energy surface. The most stable structure has a strong O…H-O hydrogen-bonding interaction, and the calculated bonding energy of it is - 68.03 kJ·mol^-1. A normal-mode analysis of the vibrations of the four isomers was carried out. The charge transfer（CT） and their corresponding second-order interaction energies were studied by nature bond orbital （NBO） analysis. The solvent effects on the geometries of equilibrium isomers and energies systematically studied by self-consistent reaction field technique with different dielectric constants of 1.0, 2. 247, 4.9, 7.58, 10.36, 20.7, 38.2,46.7 and 78.39. It was found that the solvent effect would enhance significantly the strength of hydrogen bond as shown by the decrease of the O…H distance. The solvent effect was obvious when ε was in 1.0-20.7 and was weak when e exceeded 38.2.

关 键 词：密度泛函理论 三氯乙酸一三氯乙酸复合物 基组重叠误差 红外光谱 自洽反应场 

分 类 号：O641.121[理学—物理化学]