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Quasi-classical trajectories study of Ne2Br2(B) vibrational predissociation: Kinetics and product distributions

The vibrational predissociation of the Ne2Br2(B) van der Waals complex has been investigated using the quasi-classical trajectory method (QCT), in the range of vibrational levels v' = 16-23. Extensive comparison is made with the most recent experimental observations [Pio et al., J. Chem. Phys. 133, 014305 (2010)], molecular dynamics with quantum transitions (MDQT) simulations [Miguel et al., Faraday Discuss. 118, 257 (2001)], and preliminary results from 24-dimensional Cartesian coupled coherent state (CCCS) calculations. A sequential mechanism is found to accurately describe the theoretical dynamical evolution of intermediate and final product populations, and both QCT and CCCS provide very good estimates for the dissociation lifetimes. The capabilities of QCT in the description of the fragmentation kinetics is analyzed in detail by using reduced-dimensionality models of the complexes and concepts from phase-space transport theory. The problem of fast decoupling of the different coherent states in CCCS simulations, resulting from the high dimensionality of phase space, is tackled using a re-expansion scheme. QCT ro-vibrational product state distributions are reported. Due to the weakness of the vdW couplings and the low density of vibrational states, QCT predicts a larger than observed propensity for Δv' = -1 and -2 channels for the respective dissociation of the first and second Ne atoms.