Application of nonreflecting boundary condition for numerical simulation of molecular photoionization dynamics

Simulating ionization processes on a molecular time scale requires an appro priate treatment of the ionization continuum. In general this is realized b y discretizing the ionization continuum. Since in simulations only a limite d number of discrete continuum levels can be considered, the discrete expan sion series has to be truncated at some level. Therefore, the optimal numbe r of levels used for the simulations is determined by two constraints. Firs t, the computation time has to be kept low, and second, reflection of popul ation at the last level has to be avoided. It is shown that an approximate nonreflecting boundary condition meets both requirements. The formalism has been applied to the photodissociation process of the CsCl molecule. (C) 20 00 American Institute of Physics. [S0021-8979(00)01819-3].