Abstract: The Semi-empirical method was used to study the spectral and dissociation characteristics of dibromochloromethane molecules under the action of external electric field (0-0.040 arb. units) on the AM1 basis set, the influences of external electric field on bond length, dipole moment, total energy, energy level distribution and infrared spectrum were calculated, and the dissociation potential energy curve was obtained. The results show that, when the external electric field increases from 0 arb. units to 0.040 arb. units along the y-axis direction, the bond length of dibromochloromethane molecule is obviously elongated, the molecular dipole moment increases, and the total energy first increases and then decreases. At the same time, with the increase of external electric field, the energy gap decreases, and the infrared spectrum appears red shift or blue shift. In addition, with the increase of applied electric field, the potential barrier decreases and the energy required for dissociation gradually decreases. When the external electric field reaches 0.040 arb. units, the molecule will dissociate. It is shown in this work that the 1C-3Cl bond of is dibromochloromethane molecule is easily broken under the external electric field, which provides a theoretical basis for the degradation of dibromochloromethane.

Key words: spectroscopy, dissociation potential energy, external electric field, dibromochloromethane