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SOLID STATE & STRUCTURAL CHEMISTRY UNIT
INDIAN INSTITUTE OF SCIENCE
BANGALORE – 560 012

SEMINAR
Speaker: Ms. Puja Banerjee

Title
Non-Adiabatic Reaction Dynamics
Date & Time: Thursday 18th January, 2018 at 4.00 PM
Venue: SSCU AUDITORIUM
Abstract:
In case of both electronic transition and electron transfer reaction, adiabaticity and non-adiabaticity of potential energy surfaces play a significant role in controlling the rate, even the course of the chemical processes. When the coupling between two states of a system is large, it is said to be adiabatic states, otherwise diabatic (or non-adiabatic). A large number of important chemical and biological processes involve non-adiabatic reactions which makes this field appealing to physical chemists, biologists, material scientists and many more [1]

Marcus theory provides the foundation for understanding electron transfer reactions which is based on non-adiabatic model[3]. On the other hand, molecular Quantum mechanics, used to study electronic transitions of molecules, is dominated by Born-Oppenheimer (B-O) approximation. When two or more potential energy surfaces come close together, B-O approximation breaks down and non-adiabatic reactions enter into the reaction pathway. A large number of theories, computational methods have been proposed to study such non-adiabatic transitions. Further, recently, an experiment has been carried out, successfully for real time observation of non-adiabatic transition.

In this talk, at first, adiabatic and non-adiabatic transitions will be described, then electron transfer reaction will be discussed with the help of Marcus’s theory. Next, I shall explain non-crossing rule and conical intersection for non-adiabatic electronic transition, why B-O approximation fails to describe non-adiabatic electronic transition and introduce some popular semi-classical methods such as Landau-Zener, Ehrenfest Method and surface hopping technique[4,5,6]. Next, I will conclude my talk with the application of surface hopping method to the photochemistry of DNA nucleobases and the recent experimental observation of non-adiabatic dynamics to achive both spatial and temporal characterization of conical intersections.

References:

M. Barbatti and H. Lischka. “Nonadiabatic Deactivation of 9 H-Adenine: A Comprehensive Picture Based on Mixed Quantum− Classical Dynamics.” J. Am. Chem. Soc. 130.21 (2008): 6831-6839.
B. Bagchi, Molecular Relaxation in Liquids, Oxford University Press (2012)
R.A. Marcus, “On the Theory of Oxidation-Reduction Reactions Involving Electron Transfer I” J.Chem.Phys.1956, 24, 966.
C. Zener (1932). “Non-Adiabatic Crossing of Energy Levels”. Proceedings of the Royal Society of London A. 137 (6): 696–702
P. Ehrenfest. Z. Phys., 45:455, 1927.
J. C. Tully and R. K. Preston. J. Chem. Phys., 55:562, 1971.; J.C. Tully, JCP 93, 1061 (1990);
7. M. Barbatti, “Nonadiabatic dynamics with trajectory surface hopping method.” Wiley Interdisciplinary Reviews: Computational Molecular Science 1.4 (2011): 620-633.

ALL ARE CORDIALLY INVITED TO ATTEND

Convener

Bitnami