Test of long-range exchange-correlation kernels of time-dependent density functional theory at surfaces: Application toSi(111)2×1

Abstract

We present an application of time-dependent density-functional theory ͑TDDFT͒ to the study of the optical properties of the Si͑111͒2 ϫ 1 surface from the infrared to the ultraviolet. We have carried out ab initio calculations using different methods, from DFT to Bethe-Salpeter equation ͑BSE͒ and, within TDDFT, we have tested the ability of different kernels to describe the optical features in a wide range of energies. We find good agreement between TDDFT and BSE results, by using in TDDFT a long-range frequency-dependent exchangecorrelation kernel derived from the many-body formalism ͑the MB kernel͒. The agreement between theory and experiment is very good in the whole frequency range studied. Excitonic effects, important in the infrared part of the spectrum, are less pronounced in the visible and UV ranges.

Optical properties of two-dimensional honeycomb crystals graphene, silicene, germanene, and tinene from first principles

“…Its validity to describe excitonic effects has been demonstrated in optical spectra of bulk materials, e.g. Si [34], but also of 2D systems, such as the Si(111)2 × 1 surface [36]. Even for such low-dimensional systems it has been demonstrated that the empirical kernel appropriately describes excitonic effects in optical absorption spectra.…”

Coexistence of Negatively and Positively Buckled Isomers onn+-DopedSi(111)−2×1

“…All the computational details are the same as in Ref. [16], where only the positive isomer was considered. The resulting quasiparticle band structures of the two isomers near the " J " K line, are shown in the right panel of Fig.…”

Optical properties of the long‐range Si(110)‐(16 × 2) reconstruction from first principles

“…By construction this formula has the right asymptotic behavior of the exact TDDFT kernel. The ability of the RORO kernel to describe the surface optical response has been recently checked 24 for the simple (2 × 1) reconstruction of Si(111) and shows fairly good agreement with the results obtained using MBPT.…”