Is the Drude-Lorentz model adequate for a metallic slab within terahertz/infrared frequency range?

The effect of spatial dispersion and size-effect in the electrodynamics of metallic slabs, having been studied with the formalism of the Boltzmann kinetic equation, turns out to be qualitatively different from that predicted by the widely-used Drude-Lorentz model. In particular, within the high-frequency region, the absorption oscillates as a function of wave frequency and sample thickness. Besides, the absorption becomes sensitive to the value of the electron Fermi velocity and nontrivially depends on the electron relaxation rate. The results may be very useful for the analysis of the electromagnetic response of metal-dielectric micro- and nanostructures in the terahertz and/or infrared frequency range.