Abstract
A number of single-reference post Hartree-Fock methods, namely CIS, symmetry adopted cluster configuration interaction (SAC-CI), equation of motion coupled cluster (EOM-CCSD) and time-dependent density functional theory (TDDFT), were used to investigate the excited state properties and photochemical dissociation of hypobromous acid, HOBr. Results are in good agreement with experimental data. The decay of the excited states of HOBr in the gas phase was examined by simulating the UV photoabsorption spectrum and nonadiabatic dynamics at the TDDFT M06-2X level of theory. The spectrum, composed of 10 excited states, was simulated with the nuclear ensemble approximation, sampling a Wigner distribution with 500 points. Dynamics simulations were done with the surface hopping method, started in two separate spectral windows, at 4.0 +/- 0.25 eV and 8.0 +/- 0.25 eV, to be compared to experimental UV spectral data: Three hundred trajectories were considered from each of these windows according to their excitation probabilities. The excited-state lifetime was determined. The main photochemical channel observed were HO and Br eliminations, representing 67% of all processes. (C) 2016 Elsevier B.V. All rights reserved.