"Phase or Faith: The Molecular Aharanov-Bohm Effect in Unimolecular Reactions," by Hua Guo (University of New Mexico)

Date: 
Wednesday, November 14, 2018 - 3:00pm to 4:00pm
Series: 
AMO Seminars

Special Physical Chemistry & Atomic Molecular Optical Physics Seminar

Wednesday, November 14, 2018
** Location: 2033 Young Hall **
3:00 PM

Guest Speaker: Professor Hua Guo, Department of Chemistry and Chemical Biology, University of New Mexico

Talk Title: "Phase or Faith: The Molecular Aharanov-Bohm Effect in Unimolecular Reactions"

Abstract:

It is a standard practice in chemistry to consider reaction dynamics as nuclear motion on an adiabatic potential energy surface based on the Born-Oppenheimer approximation. This approximation, which forms a cornerstone of modern chemistry, rests on the large disparity between electronic and nuclear masses. However, it also engenders a geometric phase in electronic wavefunction when encircling a conical intersection. While non-adiabatic transitions are known to occur between different adiabatic states near a conical intersection in such processes as internal conversion, it is still commonly believed that the adiabatic dynamics can be reasonably approximated by this single-state adiabatic model. We demonstrate that adiabatic dynamics of photodissociation and unimolecular reactions can be strongly influenced by the geometric phase associated with a conical intersection along the reaction pathway, even when the energy is much lower than the crossing point. This so-called molecular Aharonov-Bohm effect can be thought as a quantum interference, which can significantly affect not only the tunneling lifetimes, but also product state distributions. These results suggest important caveats to adiabatic treatments of reaction dynamics.

Event Attachments: 
Location: 
2033 Young Hall