<i>Ab initio</i>many-body calculation of excitons in solid Ne and Ar

Galamić-Mulaomerović, S.; Patterson, Charles H.

doi:10.1103/physrevb.72.035127

Cited by 16 publications

(13 citation statements)

References 46 publications

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“…In Fig.1 we show the optical spectrum of solid argon calculated within the BSE approach, and within TDDFT both using TDLDA [18] and the MBPTderived kernel [7]. The agreement of the BSE curve with experiment (line-circles) [21] (and with previous BSE calculations [22]) is good, concerning both position and relative intensity of the first two peaks. It should be noted that the experiment shows double peaks due to spin-orbit splitting, which is not taken into account in our calculations.…”

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confidence: 63%

Efficientab initiocalculations of bound and continuum excitons in the absorption spectra of semiconductors and insulators

Sottile

Marsili

Olevano³

et al. 2007

Phys. Rev. B

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We present calculations of the absorption spectrum of semiconductors and insulators comparing various approaches: (i) the two-particle Bethe-Salpeter equation of Many-Body Perturbation Theory; (ii) time-dependent density-functional theory using a recently developed kernel that was derived from the Bethe-Salpeter equation; (iii) a scheme that we propose in the present work and that allows one to derive different parameter-free approximations to (ii). We show that all methods reproduce the series of bound excitons in the gap of solid argon, as well as continuum excitons in semiconductors. This is even true for the simplest static approximation, which allows us to reformulate the equations in a way such that the scaling of the calculations with number of atoms equals the one of the Random Phase Approximation.PACS numbers: 78.20.Bh, 71.15.Qe Time-dependent density-functional theory (TDDFT) [1] is more and more considered to be a promising approach for the calculation of neutral electronic excitations, even in extended systems [2,3]. In linear response, spectra are described by the Kohn-Sham independentparticle polarizability χ KS 0 and the frequency-dependent exchange-correlation (xc) kernel f xc . The widely used adiabatic local-density approximation [4,5] (TDLDA), with its static and short-ranged kernel, often yields good results in clusters but fails for absorption spectra of solids. Instead, more sophisticated approaches derived from Many-Body Perturbation Theory (MBPT) [6,7,8,9,10] have been able to reproduce, ab initio, the effect of the electron-hole interaction in extended systems, not least thanks to an explicit long-range contribution [6,11,12]. The latter strongly influences spectra like optical absorption or energy loss, especially for relatively small momentum transfer.Here we show that this kernel is even able to reproduce the hydrogen-like excitonic series in the photoemission gap of a rare gas solid. However the kernel has a strong spatial and frequency dependence, and its evaluation requires a significant amount of computer time. We therefore tackle the question of a parameter-free, but quick TDDFT calculation of excitonic effects in solids, which has been so far an unsolved problem, and show that a much more efficient formulation can indeed be achieved. In particular we demonstrate how it is possible for a wide range of materials to obtain good absorption spectra including excitonic effects with a static kernel leading in principle to a Random Phase Approximation (RPA)-like scaling of the calculation with the number of atoms of the system. Atomic units are used throughout the paper. The vectorial character of the quantities r, k, G, q (where k and q are vectors in the Brillouin zone, and G is a reciprocal lattice vector) is implicit. Only transitions of positive frequency (i.e. resonant contributions), which dominate absorption spectra, are considered throughout.Let us first concentrate on the absorption spectrum of solid argon. The low band dispersion, together with the small polarizability ...

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confidence: 63%

Efficientab initiocalculations of bound and continuum excitons in the absorption spectra of semiconductors and insulators

Sottile

Marsili

Olevano³

et al. 2007

Phys. Rev. B

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“…This standard rule in solid state is broken down because of the existence of flat bands. hBN provides an example of this effect, with exceptional degree as Δ LT surpasses any reported value in the literature, in particular the 360 meV in solid argon [59] where the band gap is ∼14 eV. This means the macroscopic degeneracy of the direct transitions along the KH line parallel to the c axis [Fig.…”

Section: -2mentioning

confidence: 94%

“…In hBN, Δ LT is enhanced by almost 2 orders of magnitude, a striking consequence of electronic flat bands. High values of Δ LT were reported in crystals with strongly bound excitons such as alkali halides [57,58], solid neon, and solid argon [59]. In these crystals, Δ LT follows the general scaling of the oscillator strength, that increases with the excitonic binding energy, and that is inversely proportional to the cube of the excitonic Bohr radius in the approximation of parabolic bands [60].…”

Section: -2mentioning

confidence: 99%

Flat Bands and Giant Light-Matter Interaction in Hexagonal Boron Nitride

et al. 2021

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“…III) represent a prediction for future measurements. Argon is a textbook material that has been studied extensively in the past 2,39,[45][46][47][48][49][50] for its absorption spectrum that shows a hydrogenlike bound-exciton series in which the n = 1 exciton has a strongly localized character and the higher excitons n 2 are more delocalized. 51 The energy-momentum dispersion map represented in Fig.…”

Section: Argonmentioning

confidence: 99%

Exciton dispersion from first principles

Gatti

Sottile

2013

Phys. Rev. B

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We present a scheme to calculate exciton dispersions in real materials that is based on the first-principles many-body Bethe-Salpeter equation. We assess its high level of accuracy by comparing our results for LiF with recent inelastic x-ray scattering experimental data on a wide range of energy and momentum transfer. We show its great analysis power by investigating the role of the different electron-hole interactions that determine the exciton band structure and the peculiar "exciton revival" at large momentum transfer. Our calculations for solid argon are a prediction and a suggestion for future experiments. These results demonstrate that the first-principles Bethe-Salpeter equation is able to describe the dispersion of localized and delocalized excitons on equal footing and represent a key step for the ab initio study of the exciton mobility.

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Ab initiomany-body calculation of excitons in solid Ne and Ar

Cited by 16 publications

References 46 publications

Efficientab initiocalculations of bound and continuum excitons in the absorption spectra of semiconductors and insulators

Efficientab initiocalculations of bound and continuum excitons in the absorption spectra of semiconductors and insulators

Flat Bands and Giant Light-Matter Interaction in Hexagonal Boron Nitride

Exciton dispersion from first principles

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