Year: 2026
Type: preprint
Abstract: When the coupling to a quantized field becomes weak, the leading term of the photon exchange--correlation action depends on the fluctuations of the interacting electronic system, not those of a density-matched noninteracting reference. We establish this requirement by proposing an adiabatic connection formulation of electron-photon coupling at fixed electronic density and controlling the density derivatives. Approximating the response in the integral yields a ring functional in terms of the Kohn--Sham response and electronic kernel. Exact model tests verify fourth-order rather than second-order errors. In a two-electron Hubbard dimer, the functional correctly predicts a correlation-induced polarization reversal, while two Kohn--Sham photon prescriptions don't. In an interacting quantum-dot resonator model with electron injection and escape, the functional recovers resonant photon-assisted transport missed by two Kohn--Sham photon prescriptions.
Source: arXiv (Cornell University)
Author: Zhang, Xiaoyu
Institution: University of Hong Kong
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204166984