Influence of external electric field on the molecular structure and electronic spectrum of paranitrochlorobenzene

Abstract

In order to achieve the goal of degenerating organic pollutant nitrochlorobenzene, the influence of electric field on molecular structure and electronic spectrum and so on is studied by applying an external parallel electric field. Take paranitrochlorobenzene as a study object, the method B3LYP of the density functional theory at 6-311+g(d, p) level is used to calculate its molecucar structure, dipole moments and total energies of the ground state under different external electric fields (from 0 to 0.025 a.u.) in this paper. On this basis, the time-dependent density functional theory is used to study the influences of external electric field on excited wavelength and oscillator strength of the first six excited states. The results show that bond lengths (C–Cl, C–N) increase rapidly and bond energy decrease rapidly with the increase of field intensity. At the same time, bond length (C–C, C–H) changes of benzene ring are very small, and the increases or decreases are not uniform. This illustrates that molecular degradation may lead to the fractures of bonds (C–Cl, C–N), and the benzene ring is relatively stable. what is more, the molecular total energy first increases then decreases, and the dipole moment first decreases then increases with the increase of the field intensity. In addition , the maximum absorption wavelength first slowly decreases, and then increases rapidly with the increase of the field intensity, which causes the electron transition to be relatively easy, while oscillator strength changes relatively complex in anner.