Electron-Energy-Loss Spectra of Free-Standing Silicene

Silicene is becoming one of the most important two-dimensional materials. In this work, EEL Spectra were calculated for alfa-silicene (flat), and beta-silicene (low-buckled, and theoretically the most stable). Band structures were determined using the semi-empirical Tight-Binding Method considering second nearest neighbors, sp3 model, Harrison's rule, and Slater-Koster parameterization. The dielectric function was calculated within the Random Phase Approximation and a space discretization scheme. We found that, compared to bulk Si, additional resonances appear which are red-shifted. Buckling gives rise to a richer structure at low energy.