Visualizing non-adiabatic quantum dynamics and photo-excitation processes on Excel

Abstract

We offer two Excel modules that students can use to view the real-time spatial evolution of a diatomic molecule's nuclei when two different potential energy curves governing the nucleus motion spatially cross one another or are coupled by a light field. Module 1 comprises three spreadsheets that can be used to view non-adiabatic nuclear dynamics on two crossing nuclear potential energy curves. These curves cross because there is a value of the spatial coordinate where the two curves have the same energy, which results in a non-zero probability of the probability density crossing from one potential curve to the other. Students can view non-adiabatic nuclear dynamics involving two unbounded nuclear potential curves, pre-dissociation with a bound “ionic state” to an unbound covalent state, and quantum tunneling dynamics between two bounded potential curves. Module 2 comprises two spreadsheets that can be used to view the dynamics of the photo-excitation process, i.e., where the absorption of light leads to transitions between two nuclear potentials. Students can model the light-induced transitions between nuclear potentials when the light is provided by both a continuous wave laser and a pulsed laser. These modules are included as the supplementary material and can be run on any computer that supports Excel.