Radicals in aqueous solution: assessment of density-corrected SCAN functional.

We study self-interaction effects in solvated and strongly-correlated cationic molecular clusters, with a focus on the solvated hydroxyl radical. To address the self-interaction issue, we apply the DC-r 2 SCAN method, with the auxiliary density matrix approach. Validating our method through simulations of bulk liquid water, we demonstrate that DC-r 2 SCAN maintains the structural accuracy of r 2 SCAN while effectively addressing spin density localization issues. Extending our analysis to solvated cationic molecular clusters, we find that the hemibonded motif in the [CH 3 S∴CH 3 SH] + cluster is disrupted in the DC-r 2 SCAN simulation, in contrast to r 2 SCAN that preserves the (three-electron-two-center)-bonded motif. Similarly, for the [SH∴SH 2 ] + cluster, r 2 SCAN restores the hemibonded motif through spin leakage, while DC-r 2 SCAN predicts a weaker hemibond formation influenced by solvent-solute interactions. Our findings demonstrate the potential of DC-r 2 SCAN combined with the auxiliary density matrix method to improve electronic structure calculations, providing insights into the properties of solvated cationic molecular clusters. This work contributes to the advancement of self-interaction corrected electronic structure theory and offers a computational framework for modeling condensed phase systems with intricate correlation effects.