Chemistry Seminar Series 291 (9/22/17)
September 22, 2017 - 10:00pm
Aleksey Kocherzhenko, Ph.D., University of California, Merced
Exciton models offer an opportunity to simulate the optoelectronic properties of large disordered molecular systems that cannot be adequately described either by ab initio quantum chemical methods or by band theory. Such systems include organic photovoltaic blends, natural and artificial photosynthetic complexes, and organic electro-optic materials. Exciton models are useful for studying a variety of processes including linear and nonlinear optical response, energy transfer, and charge separation. However, the computational efficiency of these models is a direct consequence of approximations that underlie their construction.
In this talk I will assess the accuracy of exciton models for calculating the absorption spectra of large chromophore aggregates, benchmarked against large-scale TDDFT calculations. I will show that accounting for the local molecular environment in the parametrization of exciton models is critical to their performance. I will also explore how these models can be used in computational studies of nonlinear refraction in electro-optic materials. Finally, I will demonstrate the convenience of exciton models for simulations of ultrafast charge separation in donor-acceptor dyads and present insights into the role of high-energy charge transfer states gained from these simulations.