苯丙氨酸体系片段CDA及轨道相互作用

采用密度泛函理论中的B3LYP方法, 在3-21G基组水平上优化气相S型苯丙氨酸（S-Phe）手性对映体的几何构型, 计算Phe分子轨道波函数及片段轨道间的电荷分解分析(CDA), 并给出片段COOH,C₆H₅和NH₂形成过程中片段间的轨道相互作用图. 结果表明: 片段COOH,C₆H₅和NH₂基于CDA的ri项最大正值分别为r₁₉,r₁₇和r₁₅, 即分子轨道的形成导致占据片段轨道的电子向交叠区域转移； 片段COOH和NH₂基于CDA的ri项最大负值分别为r₄₄和r₃₅, 即分子轨道的形成导致片段间占据片段轨道的电子从交叠区域移走.

Fragment CDA and Orbital Interaction of Phenylalanine System

Using the B3LYP method of density functional theory, we optimized the geometric configuration of the gas phase S phenylalanine (S-Phe) chiral enantiomers at the 3-21G basis set,calculated the Phe molecular orbital wave functionand charge decomposition analysis (CDA) of fragment orbit, and gave the orbital interaction diagrams of fragments COOH,C₆H₅ and NH₂ during the formation of fragments. The results show that the maximum positive values of r_i of fragments COOH,C₆H₅ and NH₂ based on CDA arer₁₉,r₁₇,r₁₅, indicating that the formation of molecular orbits leads to the transfer of electrons from the fragment orbit to overlapping regions. The maximum negative values of ri of fragmentsCOOH and NH₂ based on CDA are r₄₄ and r₃₅, indicating thatthe formation of molecular orbits results in the removal of electrons occupying fragment orbits from overlapping regions.