A number of systems in spectroscopy, astrochemistry and combustion chemistry are influenced by spin-forbidden processes between electronic states of differing spin, coupled through the spin-orbit interaction. Though typically modeled using time independent Landau-Zener theory, time dependent molecular dynamic trajectory surface hopping methods can be employed. We revisit the spin-forbidden 3B1 to 1A1 transition for SiH2 through direct on-the-fly molecular dynamics simulations incorporating the Tully's Fewest Switches trajectory surface hopping method for trajectories spanning 200 fs.  For an improved description of the hopping, the time-uncertainty method is utilized as well as the gradV method for improved momentum adjustment upon hopping.  The resulting dynamics illustrate a large distribution of associated hopping geometries and spin-orbit couplings, but their average lies near the values used in Landau-Zener analysis. Other resulting dynamical properties associated with the 3B1 to 1A1 transition will be described for both Tully's Fewest Switches and Landau-Zener methods.

Nonadiabatic dynamics description of the spin-forbidden 3B1 to 1A1 ?transition in SiH2

248th National Meeting (2014)

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