Abstract
The ground state electronic properties of bulk (W) were studied within the density functional theory (DFT). We have also analyzed the momentum- (q-) dependent loss function, dielectric constant, and optical conductivity (OC) within TD-DFT random-phase approximation (RPA). The loss function is plotted in the energy range 0–55 eV. The energy loss function spectrum shows four prominent peaks, two lower peaks below along with two sharp peaks above 30 eV. The different nature of peaks depends on the momentum transfer q. The peak caused by interband transition showed a less pronounced dispersion. From the dielectric function curve we have predicted the plasmon excitation at around 1.75 eV and calculated the corresponding plasma frequency (ωp)=26.585×1014 s−1.
Highlights
Tungsten is a hard, brittle, steel-grey metal that is difficult to work with in the very pure state, unless it is malleable and ductile [1]
Alkauskas et al studied the q-dependent loss function of bulk Ag using a computational code “exciting” based on time dependent density functional theory (TD-DFT) which is well accurate in predicting the q-dependence of interband transitions [24]
In first step q-dependent loss function was calculated with local field effect (LFE) with single q point and in the second step LFE has been neglected and loss function was obtained at different set of q points
Summary
Tungsten (derived from the Swedish phrase “tung sten,” meaning heavy stone) is a hard, brittle, steel-grey metal that is difficult to work with in the very pure state, unless it is malleable and ductile [1]. Some of the metallic crystals exhibit optical properties due to the interplay between electronic plasma screening and geometrical scattering effects [8]. Under suitable circumstances, this might be used to enhance thermal emission of photons in the visible region relative to lower frequencies and serve as a lighting technology [9]. Electron energy loss spectrometry (EELS) in the TEM is a technique to study the loss function and the dielectric tensor ε [22]. Since the information about optical and electronic properties is related to ε, the loss function is a key quantity. Alkauskas et al studied the q-dependent loss function of bulk Ag using a computational code “exciting” based on time dependent density functional theory (TD-DFT) which is well accurate in predicting the q-dependence of interband transitions [24]
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