Recent progress in the development and application of novel spectroscopic techniques, such as transient absorption and correlation spectroscopies, have reignited interest in studying nonadiabatic dynamics through conical intersections in condensed phase environments. Theoretical progress remains challenging due to the large number of relevant degrees of freedom involved—conical intersections increase the level density of states, while important bath fluctuations increase the complexity of reduced descriptions due to strong coupling or non-Markovian effects. In particular, these challenges make it difficult to identify the physical parameters that determine the experimental yield and regulate the efficiency for such microscopic processes. A canonical example of these processes is photoisomerization in which a lower-energy trans isomer is converted to its higher-energy cis isomer via relaxation through a conical intersection after photoexcitation. We have studied a model for photoisomerization dynamics coupled to a bath to find relevant parameters that control the efficiency of this process. Previous studies have elucidated the dependence of the system-bath coupling and its mechanistic effect on the trans-to-cis yield, but has been limited to the weak coupling, Markovian regime due to the use of Redfield theory. We have systematically benchmarked a number of extensions to Redfield theory in order to affordably study this system across a broader parameter regime. The ability to traverse the weak- to strong-coupling regimes has been vital to understanding appropriate ways to enhance the photoisomerization yield. Specifically, we have identified a competition between system effects and bath effects on the dynamics that control the trans-to-cis yield. This competition heavily depends on the topology of the potential energy crossing, that is whether the system has a conical intersection or merely exhibits an avoided crossing. These studies imply that it is possible to engineer an environment in which the yield is maximal. To further our understanding of this process we interpret our results under the framework of stochastic thermodynamics to identify simple variables that can optimize this yield.

Unravelling the roles of decoherence and dissipation on photoisomerization yields

2019 Spring National Meeting

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