Quantum Effects in the Dissociative Chemisorption of N₂ on Fe(111): Full-Dimensional Quantum Dynamics and Quasi-Classical Trajectory Study

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.