A THEORETICAL-STUDY OF PHOTOFRAGMENTATION AND GEMINATE RECOMBINATION OF ICN IN SOLID AR

Photodissociation of ICN in an Ar matrix is studied by molecular dynam ics with quantum transitions (MDQT) with the motion of the nuclei trea ted classically and the electronic motion quantum mechanically. Four e lectronic surfaces and their corresponding couplings are included in t he calculations. The coupling between electronic states at large I-CN internuclear distances is modeled using a diatomic in molecules (DIM) treatment of the mixing of the different spin-orbit states of iodine i nduced by the Ar atoms. For a total propagation time of 3 ps, no cage exit is found and 44% of the trajectories recombine to the ground elec tronic state. The principal mechanism for geminate recombination invol ves the reaction path (II0+)-I-3-->(II1)-I-1-->(1)Sigma(0+)(+). (C) 19 98 American Institute of Physics.