Chemistry Seminar: Dr. Elliot Taffet

The Department of Chemistry in the College of Arts and Sciences is pleased to welcome Dr. Elliot Taffet, a postdoctoral scholar at Stanford University. The seminar will be held on Zoom. Please email kldalzel@syr.edu for Zoom info.

Title: Scaling Up and Leveling Up Molecular Simulations of Excitonics

Abstract

Excitons represent a conceptual framework for describing delocalized excitations spread across multichromophoric networks inherent to solid-state photophysics and biological light-harvesting. As such, our conceptualization matters. When we conceptualize the excitonic connectivity between chromophores as shapeless dipolar interactions in the Frenkel–Förster framework, we disrespect the spatial nonuniformity and heterogeneous configuration-interaction dispersed across the disordered aggregates designed by nature and humankind. When we preconceive of the diabatic transition-energies and interdiabatic couplings spanning the space of local excitations to construct a parametrized exciton-model, we bias the resolution of the adiabatic excitons toward our preconceptions. In this talk, Dr. Taffet will present an ab initio excitonmodel—leveraging the computational power of GPU-accelerated quantum chemistry—that does away with these biases and rigorously evalulates excitonics in a configuration-complete diabatic basis for the low-lying adiabatic states. Through integrating spatial couplings for the configurational hybridization of single excitations within (local excitations) and between (charge-transfer excitations) chromophores as well as doubly excited dimeric configurations (correlated triplet pairs), the ab initio exciton-model incorporates the game-changing, overlap-driven interactions introducing state-of-the-art photophysics. He will discuss recent efforts toward completing the conceptual pictures of two such state-of-the-art photophysical mechanisms—singlet fission and thermally activated delayed fluorescence—by leveraging the quantitative data and physical insight provided by the ab initio exciton-model. He also will discuss how state-of-the-art biological light-harvesting toes the line cast by this configurational space to balance excitation-energy transfer and photoprotection through excimeric interactions.