Тип публикации: статья из журнала
Год издания: 2015
Идентификатор DOI: 10.1103/PhysRevB.92.205129
Аннотация: We use the Vienna ab initio simulation package (VASP) for evaluation of the quasiparticle spectra and their spectral weights within Hedin's GW approximation (GWA) for Fe3Si and alpha-FeSi2 within the non-self-consistent one-shot approximation G(0)W(0) and self-consistent scGWA with the vertex corrections in the particle-hole channel, taken in the form of two-point kernel. As input for G(0)W(0), the band structure and wave functions evaluated within the generalized gradient corrected local-density approximation to density functional theory (GGA) have been used. The spectral weights of quasiparticles in these compounds deviate from unity everywhere and show nonmonotonic behavior in those parts of bands where the delocalized states contribute to their formation. The G(0)W(0) and scGWA spectral weights are the same within 2%-5%. The scGWA shows a general tendency to return G(0)W(0) bands to their GGA positions for the delocalized states, while in the flat bands it flattens even more. Variable angle spectroscopic ellipsometry measurements at T = 296 K on grown single-crystalline similar to 50-nm-thick films of Fe3Si on n-Si(111) wafer have been performed in the interval of energies omega similar to (1.3-5) eV. The comparison of G(0)W(0) and scGW theory with experimental real and imaginary parts of permittivity, refractive index, extinction and absorption coefficients, reflectivity, and electron energy loss function shows that both G(0)W(0) and scGW qualitatively describe experiment correctly, the position of the low-energy peaks is described better by the scGW theory, however, its detailed structure is not observed in the experimental curves. We suggest that the angle-resolved photoemission spectroscopy experiments, which can reveal the fine details of the quasiparticle band structure and spectral weights, could help to understand (i) if the scGWA with this type of vertex correction is sufficiently good for description of these iron silicides and, possibly, (ii) why some features of calculated permittivity are not seen in optical experiments.
Журнал: PHYSICAL REVIEW B
Выпуск журнала: Vol. 92, Is. 20
ISSN журнала: 10980121
Место издания: COLLEGE PK
Издатель: AMER PHYSICAL SOC
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