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Propagators and spectra of surface polaritons in metallic slabs: Effects of quantum-mechanical nonlocality

Polariton propagator for thin aluminium slab is constructed by using $\phi=0$ gauge and nonlocal conductivity tensor which is constructed by using LDA Kohn-Sham wave functions. Dyson equation for the polariton propagator is divided in $s$ and $p$ part, and each part is solved in two steps. First step is solving the Dyson equation with only paramagnetic (non-local) part of photon selfenergy included, and second step is renormalization of such propagator because of its interaction with diamagnetic (local) polarizations. This approach enabled us to investigate these two polarization mechanisms independently of one another for the first time, as well as their mutual influence. The method is used to calculate spectra of electromagnetic excitations in the vicinity and inside of a metallic slab. Enhanced electrical field which radiate point dipole placed inside metallic slab is calculated as well. In ultraviolet region (above $\omega_p$) paramagnetic (non-local) polarization strongly modify such enhancement, which is in contradiction with commonly used diamagnetic (local) description.

surface polariton ; retardation ; enhanced radiation

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