A NEW METHOD FOR THE CALCULATION OF PHOTODISSOCIATION CROSS-SECTIONS

A time-independent quantum mechanical approach to the calculation of photodissociation cross sections is developed. The method is based on the use of a discrete variable representation (DVR) and the application of absorbing boundary conditions (ABC). Both total photodissociation cross sections and partial cross sections (hence product state distributions) are obtained using the same basic technique, but the calculation is particularly efficient when only the former quantity is required. The method is applied to the photodissociation of HCl+ for which accurate potential energy curves and dipole moment functions are available, to the photodissociation of ClCN which is a direct process, involving a single excited electronic state, and to the photodissociation of ICN which involves several strongly coupled excited electronic states. The applicability of the suggested scheme to a variety of other field-matter interaction processes is pointed out.