Nonadiabatic MD simulations of IBr$^{-}$(CO$_{2}$)$_{n}$ photodissociation

Potential energy curves for the ground and valence excited states of IBr$^{-}$ have been calculated at the MRCI level using the MOLPRO \emph{ab initio} package. Spin-orbit coupling was calculated via a spin-orbit ECP. Charge densities, transition moments, and nonadiabatic coupling matrix elements constructed from a distributed multipole analysis of the \emph{ab initio} wavefunctions~\footnote{Maslen, Faeder and Parson, Molecular Physics, 1998} were then used to carry out nonadiabatic molecular dynamics simulations of the photodissociation of IBr$^{-}$ in CO$_{2}$ clusters. Experimental studies have demonstrated a large variation in ground-state recombination times which are supported by our simulations. We propose a mechanism of excited-state trapping and a configurational transition state which leads to recombination times on the order of 10-20 ps for $n$=5,13 up to 1 ns for $n$=8,10.