Computation of Electronic Bound States in Anionic Clusters as Precursors to Solvated Electrons

Solvated electrons are highly reactive species that drive a wide range of redox reactions. In this study, we compute electronic bound states in anionic molecular clusters as model systems for solvated electrons. Our method accounts for solvent polarization induced by the excess electron and electron correlation through a hybrid two-step scheme. Across a range of electron-binding strengths, the resulting bound-state energies reproduce CCSD(T) vertical detachment energies, with fitted slopes deviating from unity by less than 5%. The absolute errors are also at least 30 meV smaller than those from commonly used MP2 and range-separated ΔSCF calculations. The corresponding bound-state wave functions reproduce the spatial distribution of the excess electron. For the tested structures, the computational cost scales quartically. Overall, our approach provides an efficient framework for describing the ground state of the excess electron within a one-orbital picture.