Adsorption thermodynamics of acrolein on Pt (1Â 1Â 1) in realistic temperature and pressure from first-principle calculations

Adsorption thermodynamics of acrolein (CH2CHHCO) on Pt (1 1 1) is investigated with adsorption free energy simulations as a function of temperature and pressure. This atomistic thermodynamic approach based on density-functional theory energies shows how adsorption modes and coverage are modified in realistic experimental conditions. The various adsorption modes of the multifunctional molecule show very similar free adsorption energies, suggesting the possible coexistence of various molecular structures on the surface. The qualitative trend shows a high coverage of η2 modes (adsorbed by the CC bond only) at low temperature, evolving to a mixture of η3-cis and η4-trans modes at lower coverage upon temperature increase.