A New Method for Simulating Molecules Interacting with Metal Surfaces

What is it about?

We develop a new method for simulating the dynamics of molecules interacting with metal surfaces. A molecule can simultaneously have highly quantum components that are very small and fast, such as electrons, and heavy, slow-moving components that are essentially classical, such as center-of-mass motion of atomic nuclei. When one adds a metal surface in the vicinity that can exchange particles and energy with the molecule, simulating the resulting dynamics is a challeing task, both from a numerical and purely theoretical point of view. In this work, we introduce a new approach for such simulations, which allows the quantum and classical parts to be treated efficiently in their own way.

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Photo by israel palacio on Unsplash

Photo by israel palacio on Unsplash

Why is it important?

Our new method allows the mixed quantum-classical approach of electronic friction and Langevin dynamics to be combined with the numerically exact hierarchical equations of motion approach. This allows then the possibility of treated quantum systems containing strong electron-electron or electronic-vibrational interactions to be treated, something that other electronic friction methods have not been able to do. Furthermore, since we provide benchmark fully quantum calculations, we are able to comment on the validity of the assumptions within the electronic friction approach.