分子团簇的量子化学研究

采用Hartree-Fock方法、密度泛函(DFT)方法(BLYP、B3LYP)和MP2方法对Se4分子团簇的各种可能构型进行了结构优化和频率分析, 结果表明有5种构型是势能面上的稳定驻点, 同时对上述4种量子化学方法计算结果的差异进行了分析。并对这5种构型的结构稳定性、几何构型、前线分子轨道、Mulliken布局分析和偶极矩进行了分析, 根据分析结果对Se4分子的某些物理和化学性质进行了预测。

A Quantum Chemistry Study of Se4 Clusters

The structural optimization and vibrational frequency analysis have been carried out for eleven designed Se4 isomers with Hartree-Fock, density functional theory and MP2 methods, indicating the five isomers are stationary points on the potential energy surface of Se4 molecules. The geometry structure analysis demons- trates that the electronical correlation obviously affects the optimization results of bond lengths, but both HF exchange and electronical correlation play important roles in the optimization of bond angles. The Frontier Molecular Orbital (FMO), Mulliken population and dipole moments of Se4 molecules have also been investigated. The analysis results of FMO show that Se4 molecules prefer negative ion to positive one. With wide LUMO-HOMO energy gaps, Se4 molecular clusters have certain chemistry stability. It can be concluded from Mulliken population analysis that Se4 molecular clusters show obvious trend of forming negative and positive ion couples. It has been anticipated from the dipole moments analysis that Se4 may have low solubility in strong polar solvent like water but can dissolve in weak polar solvent.