双水作用Met过渡态电子激发特性的图解分析

采用密度泛函理论(DFT)中的B3LYP方法, 在6-311+G(2df)基组水平上优化气相条件下甲硫氨酸(Met)分子的几何构型, 分析Met+2H₂O分子体系手性转变过程中各基元反应物的特征, 并在M06-2X/def2-TZVP下, 用含时密度泛函理论(TDDFT)方法给出隐式溶剂甲醇下Met+2H₂O分子体系手性转变过程中某过渡态体系的分子轨道(MO)、 自然跃迁轨道(NTO)和空穴-电子分布等值面图, 研究图解电子激发特征. 结果表明： 在双水分子协助下, H原子迁移形成过渡态, 导致Met分子体系结构与反应物间发生显著变化, 使分子功能发生改变.

Graphic Analysis of Electronic Excitation Characteristics of Met Transition State under Action of Double Water

Using the B3LYP mehtod of density functional theory (DFT), the author optimized the geometry of gas phase methionine (Met) molecule at the level of the 6-311+G(2df) base set, and analyzed the characteristics of each elementary reaction in the process of chiral transformation of the Met+2H₂O molecular system. Under M06-2X/def2-TZVP, the time-dependent density functional theory (TDDFT) was used to obtain the molecular orbitals (MO), natural transition orbitals (NTO) and isosurface maps of hole-electron distribution of a transition state system in the process of the chiral transition of the Met+2H₂O molecular system in the implicit solvent methanol, and the electronic excitation characteristics were studied. The results show that with the help of double water molecules, H atom migrates to form transition states, which makes the Met molecular system structure and reactants change significantly, as well as the molecular function changes.