where ∆𝐺 𝑎𝑑𝑠 𝑠𝑜𝑙𝑣 is free energy of adsorption, ∆𝐸 𝑎𝑑𝑠 𝑔𝑎𝑠 is gas phase adsorption energy obtained at the level of DFT, and ∆ 𝑠𝑜𝑙 𝑇𝐼 ∆𝐺 𝑎𝑑𝑠 is free energy of interaction between the solvent and the adsorbate/slab. Such separation can be justified from a simple bond additivity model, which shows that the "intrinsic" bond energy between an adsorbate and metal is comparable in both the gas phase and the aqueous phase. In practice, the latter term (∆ 𝑠𝑜𝑙 𝑇𝐼 ∆𝐺 𝑎𝑑𝑠 ) is approximated via classical simulations using thermodynamic integration (vide infra). This approach was previously applied for the adsorption of benzene and phenol on Pt (111) by Clabaut et al. Using this approach, similar to that prior work, we confirmed a large solvation contribution (27 kcal/mol) to the free energy of adsorption of aqueous benzene on Pt (111), which is qualitatively consistent with experiment (although the experimental coverages are unknown). At least in cases where the conformational flexibility of the adsorbed species is modest, the use of a single DFT-optimized structure is likely to provide a reasonable approximation. Note that the entropy loss upon adsorption of the organic from the gas phase state under harmonic approximation is comparable to the entropy loss from solvation, thus largely canceling the entropic contributions, and justifying their apparent omission in the above expression. Figure . An illustrative scheme for how the free energy of adsorption was calculated, which is separated into 3 parts; (1) the gas-phase adsorption energies obtained from DFT, (2) the interaction between metal and water from the GAL21 force field, and (3) the interaction between benzaldehyde and water from OPLS-AA and TIP3P water model. The solvation free energy is then calculated via conventional thermodynamic integration methods.