【摘要】 运用密度泛函理论B3LYP方法和6-311++G**基函数对甲酰胺二聚体进行结构优化与频率计算.结果表明,甲酰胺二聚体存在两个稳定氢键异构体,分别具有非平面C1对称性和平面Cs对称性.二聚体分子间有强的相互作用,经基组重叠误差BSSE和零点振动能ZPE校正后的相互作用能为-20.14和-27.40 kJ/mol.氢键的形成导致H—N伸缩振动频率红移.298.15 K和标准状态下,二聚体形成过程的Gibbs自由能为15.56和18.82 kJ/mol,显示甲酰胺二聚体的形成反应是一个非自发过程.更多还原

【Abstract】 Density functional theory B3LYP method and 6-311++G** basis set are employed to obtain the optimized geometries and the calculated frequency of formamide dimer.All calculations indicate that the formamide dimer has two stable hydrogen-bonded isomers with C1 and Cs symmetry.There is strong interaction among the dimer molecules.With the BSSE and ZPE correction the interaction energies are-20.14 and-27.40 kJ/mol,respectively.The formation of hydrogen bonds produces the red shift of H—N stretching mode.At 298.15 K and standard state,the Gibbs free energies for the generation from monomer to dimer are 15.56 and 18.82 kJ/mol,respectively,which implies the non-spontaneous process of formation of the dimer.更多还原