Dissociative electron attachment to the H2O molecule. II. Nuclear dynamics on coupled electronic surfaces within the local complex potential model

We report the results of a first-principles study of dissociative electron attachment to H2O. The cross sections were obtained from nuclear dynamics calculations carried out in full dimensionality within the local complex potential model by using the multiconfiguration time-dependent Hartree method. The calculations employ our previously obtained global, complex-valued, potential-energy surfaces for the three (B-2(1), (2)A(1), and B-2(2)) electronic Feshbach resonances involved in this process. These three metastable states of H2O- undergo several degeneracies, and we incorporate both the Renner-Teller coupling between the B-2(1) and (2)A(1) states as well as the conical intersection between the (2)A(1) and B-2(2) states into our treatment. The nuclear dynamics are inherently multidimensional and involve branching between different final product arrangements as well as extensive excitation of the diatomic fragment. Our results successfully mirror the qualitative features of the major fragment channels observed, but are less successful in reproducing the available results for some of the minor channels. We comment on the applicability of the local complex potential model to such a complicated resonant system.