The dissociative chemisorption of the N 2 molecule is the rate-limiting step in the ammonia synthesis process. Here, we carried out the full-dimensional quantum dynamics study for the dissociative chemisorption of N 2 on rigid Fe(111) based on a new, accurately fitted potential energy surface (PES). The computed dissociation probabilities reveal significant quantum effects for this heavy-diatomic reaction, as compared with the quasi-classical trajectory (QCT) results. This is due to the deep pretransition state adsorption well for this reaction, which also leads to the strong dynamical steering effects, as confirmed in the QCT calculations. The current magnitude of quantum and quasi-classical dissociation probabilities on a rigid surface agrees much better with the experimental data than the previous theoretical results with approximate surface atom motion treatment at incident energies lower than 4.0 eV. This is also the first time the full-dimensional quantum dynamics study is accomplished for the dissociative chemisorption of a heavy-diatomic molecule.
The reactivity and selectivity of bimetallic surfaces are of fundamental importance in industrial applications. Here, we report the first six-dimensional (6D) quantum dynamics study for the role of surface strain and ligand effects on the reactivity of HCl on a strained pseudomorphic monolayer of Au deposited onto a Ag(111) substrate, with the aid of accurate machine learning-based potential energy surfaces. The substitute of Au into Ag changes the location of transition state, but the static barrier height remains roughly the same as pure Au(111).The 6D quantum dynamics calculations reveal the surface strain due to lattice expansion slightly enhances the reactivity. The ligand effect due to electronic structure interactions between Au and Ag substantially suppresses the reactivity of HCl in the ground vibrational state, but promotes the reactivity via vibrational excitation at high kinetic energies. This finding can be attributed to more close interaction with Ag atoms at the transition state close to the fcc site, as well as tight transition-state region making the vibrational excitation highly efficient in enhancing the reactivity. Our study quantitatively unravels the dynamical origin of reactivity control by two metals, which will ultimately provide valuable insight into the selectivity of catalyst.
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