Minimal Optimized Effective Potentials for Density Functional Theory Studies on Excited-State Proton Dissociation

Recently, a new method [P. Partovi-Azar and D. Sebastiani, J. Chem. Phys. 152, 064101 (2020)] was proposed to increase the efficiency of proton transfer energy calculations in density functional theory by using the T [Formula: see text] state with additional optimized effective potentials instead of calculations at S [Formula: see text]. In this work, we focus on proton transfer from six prototypical photoacids to neighboring water molecules and show that the reference proton dissociation curves obtained at S [Formula: see text] states using time-dependent density functional theory can be reproduced with a reasonable accuracy by performing T [Formula: see text] calculations at density functional theory level with only one additional effective potential for the acidic hydrogens. We also find that the extra effective potentials for the acidic hydrogens neither change the nature of the T [Formula: see text] state nor the structural properties of solvent molecules upon transfer from the acids. The presented method is not only beneficial for theoretical studies on excited state proton transfer, but we believe that it would also be useful for studying other excited state photochemical reactions.