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Computational Simulation of the Photochemistry of Thioanisole

EMSL Project ID


Nonadiabatic photochemical processes are important for many significant problems in energy
sciences, life sciences, and atmospheric environment. The photodissociation of thioanisole is a
prototype of such processes. Experimental observations have suggested that conical intersections
may play an important role in this process, but the detailed mechanism is yet to be fully
understood. In this project, quantum mechanical calculations and dynamical simulations are
being used to analyze this nonadiabatic photodissociation process. Accurate full-dimensional
potential energy surfaces (PESs) of the ground and two lowest singlet excited states are needed
for the simulations. This presents a significant challenge due to the electron correlation that has
to be treated for high accuracy, the high dimensionality of the PESs, the complicated topology of
the PESs caused by conical intersections, and the wide range of geometries that have to be
covered. We are adopting and developing innovative approximations based on the Anchor Points
Reactive Potential (APRP) method to address this challenge. Progress has been made on the ab
initio calculations, diabatization, and analytical fitting of the global PESs. The PESs are being
constructed, tested and improved. Once the PESs are finished they will be interfaced with
molecular dynamics packages and will be used to perform dynamical simulations of the
photodissociation process of thioanisole. In addition to investigating the mechanism of the
process, this project also aims to develop a general protocol based on APRP to model
nonadiabatic processes, in particular photochemistry, of complex systems that are beyond the
scope of traditional methods.

Project Details

Start Date
End Date


Principal Investigator

Donald Truhlar
University of Minnesota

Team Members

Kelsey Parker
University of Minnesota

Laura Fernandez
University of Minnesota

Shaohong Li
University of Minnesota

Related Publications

Li S ,Truhlar D G 2017. "Full-Dimensional Ground- and Excited-State Potential Energy Surfaces and State Couplings for Photodissociation of Thioanisole" Journal of Chemical Physics 146():064301. 10.1063/1.4975121