Quantum mechanical deconstruction of vibrational energy transfer rate and pathways modified by collective vibrational strong coupling

TL;DR

This study uses advanced quantum simulations to reveal how collective vibrational strong coupling (VSC) modifies water's vibrational energy transfer pathways, promoting delocalization and enabling new intermolecular energy routes.

Contribution

It provides a detailed quantum mechanical analysis of how collective VSC alters vibrational energy transfer mechanisms in water molecules, revealing new pathways and delocalization effects.

Findings

VSC breaks vibrational localization, promoting delocalization.

New intermolecular vibrational pathways emerge under VSC.

VET manipulation depends on transition dipole alignment.

Abstract

Recent experiments have demonstrated that vibrational strong coupling (VSC) between molecular vibrations and the optical cavity field can modify vibrational energy transfer (VET) processes in molecular systems. However, the underlying mechanisms and the behavior of individual molecules under collective VSC remain largely incomplete. In this work, we combine state-of-the-art quantum vibrational spectral calculation, quantum wavepacket dynamics simulations, and ab initio machine-learning potential to elucidate how the vibrational dynamics of water OH stretches can be altered by VSC. Taking the (H$_2$O)$_{21}$-cavity system as an example, we show that the collective VSC breaks the localization picture, promotes the delocalization of OH stretches, and opens new intermolecular vibrational energy pathways involving both neighboring and remote water molecules. The manipulation of the VET process relies on the alignment of the transition dipole moment orientations of the corresponding vibrational states. The emergence of new energy transfer pathways is found to be attributed to cavity-induced vibrational resonance involving OH stretches across different water molecules, along with alterations in mode coupling patterns. Our fully quantum theoretical calculations not only confirm and extend previous findings on cavity-modified energy transfer processes but also provide new insights in energy transfer processes under collective VSC.