Monte Carlo simulations of Ag2+ and Ag2 in aqueous solution

We perform Monte Carlo simulations of Ag-2(+) and Ag-2 in aqueous solution. We find that the hydration enthalpies are -5.56 eV for Ag-2(+) and -0.08 eV for Ag-2, and that the redox potential is -2.0 V/NHE for the Ag-2(+)/Ag-2 couple. This redox potential is less negative than that of the Ag+/Ag couple, in agreement with the general,trend, known for larger clusters. Our simulations qualitatively reproduce the absorption spectrum of Ag-2(+), observed in pulse radiolysis. We discuss the methods of calculation of the polarization and of the ionization free energy.