24.10.23 - Johan Runeson "Quantum dynamics with classical trajectories"

 

In this seminar, I will tackle the challenge of seamlessly integrating quantum and classical dynamics into numerical simulations, applicable to a wide array of physical scenarios including photoexcited dynamics, condensed-phase reactions, and energy transfer in biological systems. A computationally inexpensive strategy to simulate these processes is by an ensemble of classical trajectories.  However, when dealing with quantum systems spanning multiple surfaces, constructing such trajectories is challenging.

This seminar introduces two advancements in addressing this problem. The first is to map the quantum subsystem onto a classical counterpart, building upon the groundwork of Meyer, Miller, Stock, and Thoss, demonstrating how complex problems can be represented in terms of harmonic oscillators and spins. The second is a new algorithm for surface hopping, which resolves fundamental shortcomings of what has been the dominant method in the field since 30 years. This breakthrough simplifies accurate atomistic simulations of general nonadiabatic dynamics, offering a promising solution to a longstanding challenge in our community.