Venue: CHEM 1640
Bio: Anna Krylov is a Gabilan Distinguished Professor in Science and Engineering, Chemistry at the University of Southern California. She received her M.Sc. in Chemistry from Moscow State University and later her Ph.D. from The Hebrew University of Jerusalem. Upon completing her Ph.D. in 1996 (summa cum laude), she joined the group of Prof. Martin Head-Gordon at the University of California, Berkeley as a postdoctoral research associate, where she first became involved with electronic structure method development. In 1998, she joined Department of Chemistry at USC. Currently, Prof. Krylov leads a research group focused on theoretical modeling of open shell and electronically excited species. She is the head of the Center for Computational Studies of Electronic Structure and Spectroscopy of Open-Shell and Electronically Excited Species, iOpenShell, supported by the National Science Foundation (2005–2011) and the University of Southern California. She is developing robust black-box methods aiming to describe complicated multi-configurational wave functions in a single-reference formalism, such as coupled-cluster and equation-of-motion (or linear response) approaches. She has developed the spin-flip approach, which extends coupled-cluster and density functional methods to diradicals, triradicals, and bond-breaking. Using computational chemistry tools, and in collaboration with numerous experimental groups, Krylov is also investigating the role that radicals and electronically excited species play in such diverse areas as combustion, gas- and condensed-phase chemistry, solar energy applications, bioimaging, and ionization-induced processes in biology. She has co-authored more than 120 publications and has delivered more than 130 invited lectures. (Source https://en.wikipedia.org/wiki/Anna_Krylov)
Singlet fission (SF), a process in which one singlet excited state is converted into two triplet states, is of interest in the context of organic photovoltaic technology. Owing to its technological significance, the mechanism of SF has been vigorously investigated. Yet, the design principles for materials capable of efficient SF remain elusive. The main challenge faced by theory is a complex and intricate electronic structure of the process, which involves non-adiabatic transitions between strongly correlated states. This lecture will discuss electronic structure of the relevant states, the nature of non-adiabatic couplings, and the connection between electronic factors and rates, emphasizing the methodological aspects of the problem. The utility of theory will be illustrated by examples. Recent experimental and theoretical studies of SF in covalently linked tetracene dimers shed light on the effect of the linkers on the electronic factors and SF rates, illuminating the role of through-space and through-bond interactions between the chromophores. The results highlight the importance of integrative approaches that evaluate the overall rate, rather than focus on specific electronic factors, such as energies or couplings.