Spectrum and Dissociation Characteristics of Methyl Bromide in External Electric Field

Abstract

B3LYP/6-311++g(d, p) method is adopted to optimize ground state structure of CH 3 Br molecule. Bond length, energy gap and dissociation potential energy surface of CH 3 Br molecule in external electric field (0-0.05 a.u.) are studied. It shows that direction and magnitude of applied electric field is of great significance to molecular structure and potential energy surface. With negative electric field (C-Br bond direction) increases from 0 to 0.05 a.u., bond length of C-Br bond decreases first and then increases. Bond length of C-H bond increases gradually. Molecular energy gap E G decreases gradually. Vibrational frequency of C-Br bond increases while IR vibration frequency decreases. It is found that potential energy of methyl bromide molecule decreases and dissociation barrier decreases, which indicating that CH 3 Br molecule is easy to be excited and dissociated in external electric field.