Heterogeneous catalyzed processes are highly significant to the chemical industry. Dissociative chemisorption (DC) of molecules on surfaces is always considered as a step with a high degree of rate... Show moreHeterogeneous catalyzed processes are highly significant to the chemical industry. Dissociative chemisorption (DC) of molecules on surfaces is always considered as a step with a high degree of rate control for heterogeneous catalysis. Our ability to comprehend the different mechanisms underlying DC on metal surfaces could benefit significantly from the availability of an accurate database for the barrier heights of elementary molecule-metal surface reactions. In this work, we used a recent implementation of specific reaction parameter (SRP) to density-functional theory (DFT) (SRP-DFT) to develop potential energy surfaces (PESs) for molecule-surface reactions. The PESs were used for molecular beam simulations and compared with molecular beam experiments. The barrier heights extracted from these PESs are now used for benchmarking. Show less
Fundamental understanding of molecular reactions on metal surfaces is important for improving heterogeneous catalysis. Therefore, the reaction of small molecules on well-defined metal surfaces is... Show moreFundamental understanding of molecular reactions on metal surfaces is important for improving heterogeneous catalysis. Therefore, the reaction of small molecules on well-defined metal surfaces is investigated with state-of-the-art DFT calculations. Efforts are made to improve the agreement between experiment and theory by employing density functionals belonging to a higher level of theory than typically used. Furthermore, molecular dynamics are performed both with ab initio calculations and precomputed potential energy surfaces to investigate reaction mechanisms. This way dynamical aspects of reaction mechanisms can be investigated, e.g., the effect of rovibrational excitation of a molecule on the reaction probability and mechanism. Show less
Nour Ghassemi, E.; Wijzenbroek, M.; Somers, M.F.; Kroes, G.J. 2017
Using semi-empirical density functional theory and the quasi-classical trajectory (QCT) method, a specific reaction parameter (SRP) density functional is developed for the dissociation of... Show moreUsing semi-empirical density functional theory and the quasi-classical trajectory (QCT) method, a specific reaction parameter (SRP) density functional is developed for the dissociation of dihydrogen on Pt(1 1 1). The validity of the QCT method was established by showing that QCT calculations on reaction of D2 with Pt(1 1 1) closely reproduce quantum dynamics results for reaction of D2 in its rovibrational ground state. With the SRP functional, QCT calculations reproduce experimental data on D2 sticking to Pt(1 1 1) at normal and off-normal incidence with chemical accuracy. The dissociation of dihydrogen on Pt(1 1 1) is non-activated, exhibiting a minimum barrier height of −8 meV. Show less
In this thesis we attempt to understand several aspects of the gas-surface physics/chemistry of (a) the dissociative chemisorption of CH4 on the Ni(111) surface and (b) N2 dissociation over the Ru... Show moreIn this thesis we attempt to understand several aspects of the gas-surface physics/chemistry of (a) the dissociative chemisorption of CH4 on the Ni(111) surface and (b) N2 dissociation over the Ru(0001) surface. Apart from their industrial importance, these systems are regarded as prototypes for molecular beam and state-specific spectroscopic experiments. We performed both static DFT and dynamical calculations to understand better: (i) the role of the vibrational normal mode specificity and the collision energy dependence of the CH4 reactivity, (ii) the possible reaction paths and dissociation dynamics of CH4 and N2, (iii) the role of different vibrational and rotational quantum states, (iv) the applicability of the Born-Oppenheimer approximation for N2 dissociation and (v) the applicability of different DFT functionals for these systems. Show less
