R型半胱氨酸体系电荷转移百分数的理论计算

Theoretical Calculation of Charge Transfer Percentage for R-Cysteine System

采用密度泛函理论中的CAM-B3LYP方法,在6-31G(d)基组水平上优化气相条件下R型半胱氨酸(R-Cys)分子的几何构型,理论研究电子激发过程中R-Cys体系片段间的电荷转移特征,并基于弛豫与非弛豫激发态密度计算片段间的电荷转移百分数.结果表明:对于SH片段,S0到S3的电荷转移百分数为57.96%;对于COOH片段,S0到S1～S5各激发态的电荷转移百分数均为负值,二者电荷转移的定性结果一致;对于NH_2片段,S0到S1和S4的电荷转移百分数分别为6.98%和31.45%.

Using the CAM-B3LYP method of density functional theory,we optimized the geometric configuration of R-Cysteine(R-Cys)molecule in gas phase at 6-31G(d)basis set,theoretically studied the charge transfer characteristics between fragments of R-Cys system during the electron excitation,and calculated the charge transfer percentage between fragments based on the excited state density of relaxation and non-relaxation.The results show that for SH fragment,the charge transfer percentage from S0 to S3 is 57.96%.For COOH fragment,the charge transfer percentages of the excited states from S0 to S1-S5 are negative,and the qualitative results of charge transfer are consistent.For NH2 fragments,the charge transfer percentages from S0 to S1 and S4 are 6.98% and 31.45%,respectively.