Resonant Tunneling in Chemistry from Quantum Trajectory Base Method

International audienceOwing to its reactivity enhancing properties, quantum tunneling represents one of themost crucial effects to account for in order to achieve accurate prediction of rateconstants for numerous chemical processes[1], even at ambient temperature[2]. Overthe years, efficient methods emerged to accurately reproduce quantum tunneling inapproximate atomistic simulations, with much progress being made on assessing themultidimensional character of the optimal tunneling path[3]. However resonanttunneling still proves to be a difficult phenomenon to characterize in the aforementionedmethodological framework. In this talk, we present a purely trajectory based[4]approach of great accuracy and efficiency[5] applied to potential energy profiles subjectto resonant tunneling. The working equations are a set of first order ODEs for aHamiltonian in an extended phase space with respect to its classical analog. Trajectorypropagation time enjoys a close relationship with collision lifetime, allowing to directlyrecover Smith's quantal time delay[6] at the energy of interest and thus giving furtherinsight into resonant phenomena[7]. Trajectories describing scattering states with areflection probability of nearly unity manifest strong destructive interference patterns,resulting in a very arduous numerical integration. This is reminiscent of pathologicnumerical behavior encountered by the log-derivative approach in the deep tunnelingregime[8] and constitutes a specific form of the well-known « node problem »encountered in Bohmian Dynamics[9]. To cope with the node problem, we propose anefficient semi-analytic scheme allowing trajectories to bypass nodes without significantloss of accuracy. As a result the method is a robust tool to analyse resonant reactivescattering