Dielectric response of strongly damped resonances
It is shown that the conventional description of the dielectric response of a damped resonance is incorrect if the damping is strong. We present an improved description for this response by describing quantum mechanically the coupling to the bath states responsible for the damping. In contrast to the conventional description, the corrected low-frequency response does not vanish with increasing damping and shows the expected evolution from a damped oscillatory response to a relaxational response.
Bakker, H.J. (1996). Dielectric response of strongly damped resonances. Opt. Commun., 129, 199–204.