Reactant-product decoupling approach to half-scattering problems: Photodissociation of H2O in three dimensions

In this paper, we present the RPD (reactant-product decoupling) approach to the calculation of final-state distribution in photodissociation of H${}_2$ O in three-dimensional space. Although the RPD approach was recently developed for bimolecular state-to-state reactive scattering calculations, its application to photodissociation dynamics is very attractive. Specifically in photodissociation, the interaction (reactant) component wavefunction ${\psi }_r$ (which in the present case of photodissociation is replaced by the interaction component ${\psi }_{\mathrm{int}})$ is nonzero only in the strong interaction region, which greatly simplifies the numerical calculation for ${\psi }_{\mathrm{int}}$ in comparison to that for ${\psi }_r$ in a full bimolecular reactive scattering calculation. In the following report, the time-dependent implementation of the RPD approach to the photodissociation of H${}_2$ O in three dimensions is given and the calculated rovibrational state distributions of the OH fragment are presented.