外电场下4-溴苯酚的分子结构和解离特性

Molecular Structure and Dissociation Characteristic of 4-Bromophenol Under External Electric Fields

采用密度泛函方法(DFT)和含时密度泛函方法(TDDFT)在B3LYP/6-311+G(d,p)基组水平上优化计算了在不同外电场作用下4-溴苯酚分子的物理性质,包括键长、键角、分子体系总能量、偶极矩、能隙、红外光谱、解离特性以及激发态。研究表明在外电场(0~0.03 a.u.)作用下,4-溴苯酚分子结构有明显的变化,随着外电场的增强,分子C—Br键长、O—H键长、偶极矩逐渐增大,C—O键长、分子体系总能量、能隙逐渐减小;分子红外光谱的四个吸收峰均发生红移;同时前10个激发态也发生红移;当外电场强度为0.03 a.u.时,势垒消失,分子发生解离。

Density functional theory(DFT)and time-dependent density functional theory(TDDFT)at the B3 LYP/6-311+G(d,p)level were used to calculate and optimize the physical characteristics of 4-bromophenol under the different electric fields,including the bond length,bond angle,total energy,dipole moment,energy gap,infrared spectrum,dissociation properties,and excited state.The results revealed a significant change in the molecular structure of 4-bromophenol under an external electric field(0-0.03 a.u.).The molecular C—Br bond length,O—H bond length,and dipole moment increased gradually with increasing external electric field,while the C—O bond length,total energy,and energy gap decreased gradually.The four absorption peaks of the molecular infrared spectrum showed a red shift.Simultaneously,the first 10 excited states also showed a red shift.When the external electric field intensity was 0.03 a.u.,the potential barrier disappeared,and molecular dissociation was observed.