外电场作用下黄曲霉素B1的分子结构和光谱

利用密度泛函（DFT）理论，在B3LYP/6-311G基组水平上研究外电场（0~0.015 a.u.）作用下黄曲霉素B₁（Aflatoxin B₁，AFB₁）分子的总能量、偶极矩、键长、HOMO-LUMO能隙、红外光谱.在优化构型的基础上，利用含时密度泛函（TDDFT）方法研究紫外可见吸收光谱和激发态的变化.结果表明：在CO键方向上加电场，外电场逐渐增大时，AFB₁分子的总能量逐渐增大，偶极矩逐渐减小.电场对不同的键长影响不同.能隙随外电场逐渐增大而减小，红外光谱吸收峰出现红移或蓝移，紫外可见吸收光谱的两个吸收峰发生不同的移动，但总的谱线集中在近紫外光区.分子各个激发态的激发能在外电场逐渐增大时逐渐减小，表明分子结构越来越不稳定.

Molecular Structure and Spectrum of Aflatoxin B1 Under External Electric Fields

To study influence of external field on aflatoxin B₁ (AFB₁), density functional theory on level of 6-311G is utilized. Total energy, dipole moments, geometric parameters, energy gap and infrared spectra under different external fields (from 0 to 0.015 a.u.) are obtained, respectively. UV-Vis spectra absorption of AFB₁ and excitation states are calculated with time dependent density functional theory method. It shows that total energy increases, while dipole moment decreases. Molecular geometric parameter and energy gap are strongly dependent on increasing field intensity. Two ultraviolet absorption peaks of AFB₁ show reversed shifts. Excitation energies decrease, which indicates that AFB₁ molecule is unstable under external fields.