Over-barrier crossing in multidimensional tunneling

Páll J Thorsteinsson,Niels E Henriksen

doi:10.1016/j.cplett.2021.139255

Abstract

Studies of the dissociative chemisorption of N2 using two-dimensional empirical potential energy surfaces that differ by the position of the saddle point, all show high tunneling probabilities at energies well below the saddle-point energy of the reaction. This is highly unusual for a heavy-atom system and contradicted by one-dimensional analysis along the minimum-energy path. A mechanism of over-barrier crossing, related to the high-momentum tail of the vibrational wave function of N2, is demonstrated. We analyze the two-dimensional wave-packet propagation and compares to the probability of having vibrational momenta that exceeds the value required to overcome the relevant barrier.

Highlights

It is well-known that tunneling plays an important role for chemical reactions involving light atoms like hydrogen
Studies of the dissociative chemisorption of N2 using two-dimensional empirical potential energy surfaces that differ by the position of the saddle point, all show high tunneling probabilities at energies well below the saddlepoint energy of the reaction
An empirical potential energy surface is constructed with pa rameters chosen in order to comply with known experimental data

Summary

Introduction

It is well-known that tunneling plays an important role for chemical reactions involving light atoms like hydrogen. Studies of the dissociative chemisorption of N2 using two-dimensional empirical potential energy surfaces that differ by the position of the saddle point, all show high tunneling probabilities at energies well below the saddlepoint energy of the reaction. A mechanism of over-barrier crossing, related to the high-momentum tail of the vibrational wave function of N2, is demonstrated.

Results

Conclusion