Group Additivity for Estimating Thermochemical Properties of Furanic Compounds on Pd(111)

We analyze the adsorption of 101 furan chemistry-related adsorbates, including intermediates with varying levels of hydrogenation of the furan ring as well as ring-open compounds, on Pd(111). The standard heat of formation (H_f,298), standard absolute entropy (S₂₉₈), and heat capacity (C_p,T) are estimated using dispersion-corrected density functional theory (DFT-D3) and statistical mechanics formulas, and all H_f,298 values are referenced to a single set of gas-phase molecules to ensure consistency. We further estimate the dispersion contribution, ΔE_disp, to the heat of adsorption. Subsequently, we develop a group additivity scheme to quickly estimate thermochemical properties of furanic molecules. For the proposed model, the vibrational and rotational contributions of gas-phase-like groups are estimated using G4-level calculations. We find that the group additivity scheme developed for open-chain molecules is inaccurate for furanics. We report 17 new groups, involving heteroatom–nearest neighbor interactions and four new corrections that account for furan ring deformation and the level of ring hydrogenation. The mean deviations from DFT-computed values are 1.8 kcal/mol in H_f,298, 0.3 kcal/mol in ΔE_disp, 0.9 cal/(mol K) in S₂₉₈, and 0.7 cal/(mol K) in C_p,800. The largest deviations are observed in highly saturated adsorbates with multiple gas-phase-like surface groups. We further introduce a nine-parameter heteroatom-based model for estimating ΔE_disp, resulting in a mean deviation from DFT-computed values of 1.4 kcal/mol.