Chemically Accurate Adsorption Energies: CO and H₂O on the MgO(001) Surface

Abstract

Hybrid MP2:DFT-D structure optimizations are performed at BSSE-free CBS-extrapolated potential energy surfaces for molecule–oxide surface interactions (BSSE, basis set superposition error; CBS, complete basis set limit). Subsequently single point MP2 calculations are performed to estimate the effects of increasing the basis set size in the CBS extrapolation and increasing the cluster model size. The resulting estimates of the periodic MP2 limit agree within 1 kJ/mol with Local MP2 calculations using periodic boundary conditions. Single point CCSD­(T) calculations are performed to determine ΔCC = CCSD­(T) – MP2 energy differences. The final hybrid MP2:DFT-D+ΔCC estimate for CO on the MgO(001) surface at low coverage, −21.2 ± 0.5 kJ/mol, is in close agreement with the reference energy derived from temperature-programmed desorption experiments, −20.6 ± 2.4 kJ/mol. For H2O on MgO(001), at limiting zero coverage, we predict an adsorption energy of −53.7 ± 4.2 kJ/mol which falls in the range of values, −55.8 ± 12.2 kJ/mol, derived from a high coverage low energy electron diffraction experiments and estimated lateral interactions.

Prospects of Heterogeneous Hydroformylation with Supported Single Atom Catalysts

“…Similar procedures were employed by Ugliengo et al 64 and Sauer and coworkers. 65 Trends with DFT and DLPNO-CCSD(T): Besides the absolute values of reaction energies and barriers that determine the activity and selectivity of a catalyst, we are also focusing on how changing the catalyst would affect certain reaction steps, for example by lowering a certain barrier. Trends among catalysts can be studied through the differences in reaction energy (ΔΔ ) for each intermediate and transition state for a catalyst with respect to a reference catalyst.…”

Including dispersion in density functional theory for adsorption on flat oxide surfaces, in metal–organic frameworks and in acidic zeolites

“…The list of studied systems includes adsorption of carbon monoxide, 43 as well as of monolayers of methane and ethane at the MgO(001) surface, 43 adsorption of carbon monoxide 44 and dioxide 45 in a MOF with the composition Mg 2 (dobdc) (dobdc 4À = 2,5-dioxido-1,4-benzenedicarboxylate), and adsorption of methane, ethane, and propane in H-chabazite 46 (H-CHA). A four layer MgO slab with a 4 Â 4 surface cell is adopted for CO, CH 4 , and C 2 H 6 on the MgO(001) surface.…”

Predicting adsorption selectivities from pure gas isotherms for gas mixtures in metal–organic frameworks

“…Chemical accuracy has been achieved for electronic energies by employing a quantum chemical hybrid method that uses Møller-Plesset second order perturbation theory (MP2) 39 at the adsorption site and DFT+dispersion (PBE+D2) for the full periodic structures. [40][41][42][43] For a smaller model of the adsorption site calculations are performed with Coupled Cluster theory, CCSD(T). 39 Thermal effects and entropies for CO and N 2 adsorption are obtained from vibrational partition functions with the anharmonic vibrational energies calculated for each vibrational mode separately.…”