Year: 2026
Type: preprint
Abstract: Quantitative prediction of electronic spectra in water requires an accurate treatment of electronic excitation, nuclear structure, and state-specific solvation including effects from hydrogen bonding. Here, photoacids and photobases in aqueous solution are used as stringent test systems for statespecific embedded cluster reference interaction site model calculations combined with the iterative coupled cluster models CC2 and CC3. Wigner nuclear-ensemble and adiabatic Hessian Franck-Condon calculations reproduce absorption and emission band maxima on an absolute energy scale with typical errors of 0.1–0.2 eV without empirical shift or scaling corrections; the energies of resolved 0–0 transitions in photobases are even reproduced within a few hundredths of an eV. The simulations also resolve contributions from different excited states and changes in the emitting species. Derived excited-state acidity changes, ∆pK∗ a , show similar accuracy for photoacids and photobases, with residual errors governed by cancellation or accumulation between protonation states.
Source: ChemRxiv
Institution: Ruhr University Bochum
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221595159