基于分子轨道隐式溶剂H2O下苏氨酸的电荷转移

Charge Transfer of Threonine Based on Molecular Orbit under Implicit Solvent H2O

基于分子轨道(MO)和自然跃迁轨道(NTO)成分计算分子片段间的电荷转移.先用密度泛函理论(DFT)中的CAM-B3LYP方法,在6-31G(d)基组水平上优化隐式溶剂H2O下苏氨酸(Thr)分子的几何构型,再在相同理论方法下进行含时密度泛函理论(TDDFT)的电子激发计算,给出隐式溶剂H2O下Thr分子体系电子激发过程中片段间电荷转移特征的对比结果.结果表明:在S1~S5激发态中,仅S2中有一对MO32→MO33跃迁轨道占绝对优势,可通过分析该轨道的成分讨论电荷转移;其他激发态可通过NTO分析方法讨论电荷转移;S0向激发态S1,S3和S4电荷转移的主要贡献为NTO32→NTO33轨道,与Hirshfeld和Becke方法的定性结果一致,定量结果略有差别。

The charge transfer between molecular fragments was cal culated based on components of molecular orbit (MO) and natural transition orbit (NTO),we first optimized the geometric configuration of threonine (Thr) molecule at 6-31G( d ) basis set under implicit solvent H 2O by using the CAM-B3LYP method of density functional theory. Then,we calculated the electron excitation of time dependent density functional theory (TDDFT) under the same theoretical method,and gave the results of comparing the charge transfer characteristics between fragments during the electron excitation of Thr molecular system under implicit solvent H 2O. The results show that in the S1-S5 excited state, only a pair of MO32→MO33 transition orbits are dominant in the S2,and the cha rge transfer can be discussed by analyzing the orbital components of the orbit, charge transfer of other excited states can be discussed by NTO analysis method. The main contribution of charge transfer from S0 to excited states S1,S3 and S4 i s NTO32→NTO33 orbit,which is consistent with the qualitative results of Hirshfeld and Becke methods,and the quantitative results are slightly different.