Reactivity of an excess electron with monovalent cations in bulk water by mixed quantum classical molecular dynamics simulations

A mixed quantum classical molecular dynamics (QCMD) simulation of the silver and sodium cations in presence of an excess electron is reported. The silver cation is shown to be reduced by the hydrated electron and to form a stable, highly polarized, neutral atom. On the contrary the sodium cation is not reduced and a metastable contact ion pair is observed. The resulting absorption spectra of both species are compared with experiments and shown to be in good agreement. Furthermore, the free energy curve for the charge separation was calculated and rationalized in terms of a thermodynamic cycle. Finally, a direct, reactive, molecular dynamics trajectory provides some useful informations on the reduction mechanism.