Comparing semiclassical mean-field and 1-exciton approximations in evaluating optical response under strong light-matter coupling conditions

Bingyu Cui, Maxim Sukharev, Abraham Nitzan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The rigorous quantum mechanical description of the collective interaction of many molecules with the radiation field is usually considered numerically intractable, and approximation schemes must be employed. Standard spectroscopy usually contains some levels of perturbation theory, but under strong coupling conditions, other approximations are used. A common approximation is the 1-exciton model in which processes involving weak excitations are described using a basis comprising the ground state and singly excited states of the molecule cavity-mode system. In another frequently used approximation in numerical investigations, the electromagnetic field is described classically, and the quantum molecular subsystem is treated in the mean-field Hartree approximation with its wavefunction assumed to be a product of single molecules’ wavefunctions. The former disregards states that take long time to populate and is, therefore, essentially a short time approximation. The latter is not limited in this way, but by its nature, disregards some intermolecular and molecule-field correlations. In this work, we directly compare results obtained from these approximations when applied to several prototype problems involving the optical response of molecules-in-optical cavities systems. In particular, we show that our recent model investigation [J. Chem. Phys. 157, 114108 (2022)] of the interplay between the electronic strong coupling and molecular nuclear dynamics using the truncated 1-exciton approximation agrees very well with the semiclassical mean-field calculation.

Original languageEnglish
Article number164113
Number of pages10
JournalJournal of Chemical Physics
Volume158
Issue number16
DOIs
StatePublished - 28 Apr 2023

Funding

FundersFunder number
National Science FoundationCHE1953701
Air Force Office of Scientific ResearchFA9550-22-1-0175

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