Abstract:
Excitation energy transfers constitute key steps in many processes occurring with light-matter interactions. While electronic excitations and deexcitations are fundamental elements in those processes, vibrations also play important roles through coupling to electronic states. Toward elucidating their fundamental aspects, from a theoretical perspective, harmonic vibrations have been continually adopted as bath models for simulating quantum dynamics. However, molecular vibrations are inherently anharmonic and the importance or unimportance of anharmonicities is something that requires further discussion. The related obstacle is the fact that treating anharmonicity requires accurate potential energy surface information, which is either too unreliable or too expensive. In this presentation, we will discuss recent efforts toward performing all-atomistic simulations in both reliable and economical ways. We adopt the energy transfer process within the light-harvesting 2 (LH2) complex as a test case, and find that the conventional harmonic oscillator model can practically reproduce vibronic coupling observed with the actual system from the perspective of electronic degrees of freedom. However, it fails to correctly capture the non-equilibrium dynamics of the vibrational motions and their energy flows. Moreover, the broadening of the coupling spectrum for underdamped intramolecular vibrations can only be well described with anharmonicity. Future prospects for generalizing the present findings will also be discussed.
Biography:
Young Min Rhee obtained his Ph.D. degree at Stanford University (advisor Prof. Vijay Pande) in 2005. After working as a postdoctoral researcher at the University of California, Berkeley (advisor Prof. Martin Head-Gordon) until 2008, he joined the faculty of the Department of Chemistry at POSTECH in Korea. In 2017, he moved to KAIST where he became a full professor in 2019. His main research interest lies on studying excited state dynamics of complex systems and developing methodologies for handling related systems.
Seminar Series by the NYU-ECNU Center for Computational Chemistry at NYU Shanghai
This event is open to the NYU Shanghai, NYU, ECNU community and the computational chemistry community.