Ab Initio Calculation of Rate Constants for Molecule–Surface Reactions with Chemical Accuracy

Abstract

The ab initio prediction of reaction rate constants for systems with hundreds of atoms with an accuracy that is comparable to experiment is a challenge for computational quantum chemistry. We present a divide‐and‐conquer strategy that departs from the potential energy surfaces obtained by standard density functional theory with inclusion of dispersion. The energies of the reactant and transition structures are refined by wavefunction‐type calculations for the reaction site. Thermal effects and entropies are calculated from vibrational partition functions, and the anharmonic frequencies are calculated separately for each vibrational mode. This method is applied to a key reaction of an industrially relevant catalytic process, the methylation of small alkenes over zeolites. The calculated reaction rate constants (free energies), pre‐exponential factors (entropies), and enthalpy barriers show that our computational strategy yields results that agree with experiment within chemical accuracy limits (less than one order of magnitude).

Insight into the Role of Water on the Methylation of Hexamethylbenzene in H‐SAPO‐34 from First Principle Molecular Dynamics Simulations

“…The electronic level of theory adopted in this study is commonly used in zeolite catalysis due to its computational efficiency. Detailed level of theory studies have been performed on various zeolite catalyzed reactions, which show that barriers may be severely underestimated using the PBE‐D method . Seminal work was done by Sauer and co‐workers to compare the accuracy of commonly used DFT methods in combination with various schemes to include the dispersion interactions.…”

“…Detailed level of theory studies have been performed on various zeolite catalyzed reactions, which show that barriers may be severely underestimated using the PBE-D method. [28,[95][96][97][98] Seminal work was done by Sauer and co-workers to compare the accuracy of commonly used DFT methods in combination with various schemes to include the dispersion interactions. They also considered more accurate but also computationally more demanding methods which include contributions from the Møller-Plesset perturbation theory (MP2) or methods where the exact exchange is combined with correlation treated in the random phase approximation.…”

Accurate adsorption energies for small molecules on oxide surfaces: CH4/MgO(001) and C2H6/MgO(001)

“…However, knowledge about the accuracy of the different approaches for different surface problems is still limited, mainly because of a lack of reliable reference data. This is the motivation for building a set of molecule–surface interactions for which agreement within chemical accuracy limits has been reached between ab initio calculations and reliable experiments . Here, we are taking steps toward quantum chemical reference data for experimentally well‐known systems, namely methane and ethane molecules adsorbed on the simplest oxide surface, MgO(001) …”

Ewald Wicke Prize: G. Piccini / Nernst–Haber–Bodenstein Prize: E. H. G. Backus and J. Paier / Elected to the Leopoldina: S. Grimme and H. Rübsamen‐Schaeff

“…Piccini is currently working on the development and application of enhanced sampling methods for studying complex chemical reactions. He is co‐author of a report in Angewandte Chemie on the ab initio calculation of rate constants for molecule–surface reactions …”