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

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) at the B3LYP/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 harrier disappeared, and molecular dissociation was observed.