A quasiclassical trajectory study of vibrational predissociation of van der Waals molecules: Collinear He⋅⋅⋅I2(<i>B</i> 3Π)

Abstract

Vibrational predissociation of the van der Waals molecule He⋅⋅⋅I2(B 3Π) has been investigated using quasiclassical trajectories. The study was restricted to collinear motion to allow comparisons with the quantum mechanical calculations of Beswick and Jortner [J. Chem. Phys. 68, 2277 (1978); 69, 512 (1978)]. The unimolecular dissociation of He⋅⋅⋅I2(B 3Π) confined to a single adiabatic electronic potential-energy surface was studied as a function of the initial I2 vibrational quantum state, where a zeroth-order approximation of the separation of the I–I and He–I2 oscillators was made for the purpose of assigning initial states. The computed trajectory results show that the unimolecular decay as a function of time obeys the exponential decay law quite well. The computed decay rates are in accord with the quantum mechanical values and with experimental measurements.