title: On the photophysics and photochemistry of the water dimer.
abstract: The photochemistry of the water dimer irradiated by UV light is studied by means of the complete active space perturbation theory//complete active space self-consistent field (CASPT2//CASSCF) method and accurate computational approaches like as minimum energy paths. Both electronic structure computations and ab initio molecular dynamics simulations are carried out. The results obtained show small shifts relative to a single water molecule on the vertical excitation energies of the dimer due to the hydrogen bond placed between the water donor (W(D)) and the water acceptor (W(A)). A red-shift and a blue-shift are predicted for the W(D) and W(A), respectively, supporting previous theoretical and experimental results. The photoinduced chemistry of the water dimer is described as a process occurring between two single water molecules in which the effect of the hydrogen bond plays a minor role. Thus, the photoinduced decay routes correspond to two photodissociation processes, one for each water molecule. The proposed mechanism for the decay channels of the lowest-lying excited states of the system is established as the photochemical production of a hydrogen-bonded H(2)O...HO species plus a hydrogen H atom.
authors.affiliation: Instituto de Ciencia Molecular, Universitat de València, P.O. Box 22085, 46071 València, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Segarra-Martí
authors.forename: Daniel
authors.initials: D
authors.lastname: Roca-Sanjuán
authors.forename: Manuela
authors.initials: M
authors.lastname: Merchán
authors.forename: Roland
authors.initials: R
authors.lastname: Lindh