REFERENCE INTERACTION SITE MODEL POLARON THEORY OF THE HYDRATED ELECTRON

We have extended the reference interaction site model (RISM)-polaron theory of Chandler et al. [J. Chem. Phys. 81, 1975 (1984)] to treat self-trapping and localized states of excess electrons in polar fluids. The extension is based on a new closure of the RISM equation presented herein. The theory is applied to the hydrated electron employing a simple class of electron-water pseudopotentials. Included in this class are models coinciding with those already examined by others using computer simulations. In those cases, the results for both structural and energetic properties compare well with those of simulation. The work function, or equivalently, the excess chemical potential of the hydrated electron are also computed; the theoretical result agrees with experiment to about 1%. Most interesting, however, is that as the parameter characterizing the pseudopotentials is varied, a critical parameter is found where the electron behavior changes essentially discontinuously from a trapped state to a "super"-trapped state. This transition may have a direct bearing on theoretical efforts to explain the properties of solvated electrons.