David R. Yarkony
Theoretical Chemical Physics
Johns Hopkins University
3400 North Charles St.
Baltimore, MD 21218
PhD - University of California, Berkeley
Post Doctoral Fellow - Massachusetts Institute of Technology
Theoretical Studies of Electronically Nonadiabatic Processes
According to the Born-Oppenheimer approximation nuclei move on a single potential energy surface created by the faster moving electrons. This approximation is at the heart of our description of most chemical processes. From protein folding to tribology to catalysis the Born Oppenheimer approximation rules. So why study nonadiabatic processes, processes in which the Born-Oppenheimer approximation breaks down. The answer is simple in the absence of nonadiabatic processes life on earth as we know it would not exist. Light harvesting, vision and a variety of essential upper atmospheric processes depend on electronically nonadiabatic steps.
Of course this has been known for decades. What is unusual and exciting isthat in the last 10 years our way of thinking about electronically nonadiabatic processes has begun to change, and change dramatically. The changing face of nonadiabatic chemistry is the consequence a rethinking of the role of surface intersections ( conical intersections) of states of the same symmetry these processes. Once little more than a theoretical curiosity today conical intersections of two states of the same symmetry are now understood to be an essential aspect of nonadiabatic processes. This change in paradigm can dramatically change the predicted/expected rate of a nonadiabatic process.
My research group has helped lead this revolution. Over the last decade we have developed the tools for studying conical intersections that define the state of the art in this area and as a are result have lead the way in advancing the computational description of this singular consequence of the separation of nuclear and electronic time scales. Presently we are building on our expertise in the description of the electronic structure aspects of this problem by developing fully quantum mechanical wave packet methods to study the dynamics of nonadiabatic processes induced by conical intersections.
In summary nonadiabatic chemistry is an important field with a bright new future and we expect to play a leading in this area.