Connecting finite size charge-transfer-to-solvent energy to the bulk: A general microscopic theory

► Microscopic theory based general expression is derived for size dependent CTTS energy. ► This general expression is true for any unknown interaction potential. ► It extracts bulk CTTS energies within 3% of the experimentally measured ones for halide-water clusters. ► A linear correlation between size selected VDE and CTTS energy is observed.