Communications: A model study on the electronic predissociation of the NeBr(2) van der Waals complex.

Recently, the predissociation lifetimes of the NeBr(2)(B) complex for different initial vibrational excitation (10<or=v(')<or=20) have been measured using time-resolved optical pump-probe spectroscopy [Taylor et al., J. Chem. Phys., 132, 104309 (2010)]. In the vibrational interval studied, the vibrational predissociation (VP) proceeds by the transfer of a single vibrational quantum and the lifetimes are expected to decrease smoothly with increasing v('), as predicted by the energy gap law. However, the experimental lifetimes show strong oscillations with v('), which were attributed to the occurrence of electronic predissociation into two possible dissociative electronic states of Br(2)(1(g),2(g)), based on a Franck-Condon spectator model. In this work we reproduce the experimental findings by performing full three-dimensional wave packet calculations for the competition of vibrational and electronic predissociation, including the B(0(u) (+)), 2(g), and C(1(u)) electronic states. Model potential energy surfaces were used based on previous theoretical simulations of the VP dynamics on the B state and on ab initio calculations on the NeCl(2) related system. Thus, only two parameters, the strength of the electronic couplings, are fit to achieve the excellent theoretical/experimental agreement.