Dr. Nađa Došlić, Institut Ruđer Bošković, Kroatia

Strategies for Modelling and Monitoring Photochemical Processes: Progress and Challenges

Start Date 05.10.2021 - 17:00
Event End 05.10.2021 - 18:00
Location University of Zurich, Department of Chemistry
Lecture Hall Y03-G-95
Website

The theoretical study of chemical processes involving excited electronic states is a subject of fundamental and practical importance. This talk presents our strategies for modelling these processes.
One usually starts with the theoretical assignment of electronic spectra. In complex molecules this is a challenging problem which requires the determination of the diabatic character of a large number of electronic states. We will discuss a procedure for automatically determining the characters of electronic transitions and apply it for the assignment of UV absorption spectra of the five nucleobases in the gas phase and in aqueous solution.
In photochemical reactions, the time-dependent population probabilities of electronic states are the observables of interest. By comparing a range of methods for solving the time dependent Schrödinger equation we show that trajectory-based mixed quantum-classical methods which account for switching between electronic states, but otherwise neglect nuclear quantum effects, are well suited to deliver this information. The methodology is illustrated for photophysical and photochemical processes of recent interest.
We focus then on methods for monitoring photochemical reactions and discuss a theoretical framework for the simulation of femtosecond time resolved transient absorption and photoionization spectra using trajectory-based methods.