Density-Functional Theory of Excitation Spectra of Semiconductors: Application to Si

Wang, C. S.; Pickett, Warren E.

doi:10.1103/physrevlett.51.597

Cited by 252 publications

(84 citation statements)

References 18 publications

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“…A comparison between the experimental direct optical transition energies This kind of agreement is a dramatic improvement over previous theories [11][12][13][14]. In fact, the present results are comparable to results from empirical methods [22] in which the band structure is obtained by fitting to optical data using several parameters.…”

Section: Quasiparticle Theorysupporting

confidence: 77%

“…This situation has stimulated much recent theoretical activities, and several many-body approaches have been proposed. [10][11][12][13][14] In this paper, we give an overview of some results from a recently developed first-principles theory of quasiparticles. [10] The approach is based on evaluation of the electron self-energy to first order in the dynamically screened Coulomb interaction, the GW approximation.…”

Section: Introductionmentioning

confidence: 99%

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Theory of quasiparticle energies: Band gaps and excitation spectra in solids

Louie

Hybertsen

1987

Int. J. Quantum Chem.

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A first‐principles theory for the band gaps and electronic excitation energies in crystals is described. Optical and photoemission spectra are properly interpreted as transitions between quasiparticle states of the many‐electron system. The theory requires adequate treatment of the Coulomb interaction between the electrons, including exchange and dynamical correlation effects. The nonlocal energy‐dependent electron self‐energy operator is evaluated from first principles using the full dielectric matrix and the dressed Green's function. Quasiparticle energies for materials covering a wide range of metallicity and ionicity are presented. With no empirical input, the calculated band gaps, optical transition energies, and band dispersions are all within a few percent of experimental values. For semiconductors and insulators, we find that local field effects in the screening of the Coulomb interaction and dynamical renormalization are both crucial for accurate results. The present method also extends beyond the case of bulk crystals, e.g., to surfaces. Results on the surface state energies of the Ge (111): As and S(111):As surface are discussed and compared with experiment.

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Section: Quasiparticle Theorysupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Theory of quasiparticle energies: Band gaps and excitation spectra in solids

Louie

Hybertsen

1987

Int. J. Quantum Chem.

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“…This approach is motivated by the fact that a GW calculation with (hypothetical) metallic screening approximately reproduces the LDA spectrum. [20][21][22][23] It is thus mainly the difference between metallic and the real nonmetallic screening, which causes QP corrections for nonmetals, e.g., for the organic molecule of the present study.…”

Section: Introductionmentioning

confidence: 90%

“…We therefore employ a simplified, perturbative LDA + GdW approach, [20][21][22] QP corrections from LDA + GdW differ from standard GW data by less than 20%. [20][21][22][23] For gas-phase PTCDA, LDA + GdW can be checked against a standard GW calculation and against experiment. Figure 2(a) shows that the GdW shifts (−1.8 eV for the HOMO and +1.7 eV for the LUMO) agree well with standard GW data (both with our own and with those of Ref.…”

Section: Mean-field Spectrum From Mbptmentioning

confidence: 99%

Ab initiostudy of a mechanically gated molecule: From weak to strong correlation

et al. 2011

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The electronic spectrum of a chemically contacted molecule in the junction of a scanning tunneling microscope can be modified by tip retraction. We analyze this effect by a combination of density-functional, many-body perturbation, and numerical renormalization-group theories taking into account both the nonlocality and the dynamics of electronic correlation. Our findings, in particular the evolution from a broad quasiparticle resonance below to a narrow Kondo resonance at the Fermi energy, correspond to the experimental observations.

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“…Therefore the LDA electronic structures should be reliable. 25) Due to the presence of doped nitrogen atoms, the system does not have the tetragonal symmetry any more. However, we use the symmetry-point notations of the tetragonal pristine phase with the same supercell size.…”

Section: )28)mentioning

confidence: 99%

Energetics and electronic properties of heavily nitrogen-doped titanium dioxide

Aoki

Saito

2013

J. Ceram. Soc. Japan

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We study nitrogen-doping effects on the energetics and electronic properties of titanium dioxide (TiO 2 ) at high doping concentrations using the first-principles electronic-structure study. From the defect formation energies obtained, it is confirmed that nitrogen atoms should tend to be clustered in the heavily-doped system. This clustering should occur because dopants share the surrounding distorted region and then the lattice-distortion energy per dopant become smaller if dopants are located at shorter distances. We also find that the impurity-induced states seem to be sufficiently hybridized with the original valence band in all the cases studied. The system would show the photoabsorption spectrum expanding to the longer-wavelength region down to around 620 nm in rutile and 730 nm in anatase if nitrogen atoms are sufficiently doped.©2013 The Ceramic Society of Japan. All rights reserved.Key-words : Titanium dioxide, Nitrogen doping, Photocatalysis, Electronic structure, Defect formation energy, DFT [Received November 29, 2012; Accepted February 5, 2013] Titanium dioxide (TiO 2 ) is one of the most basic materials for photocatalytic applications.1) Because photocatalytic materials activate some kinds of chemical reactions by photo-excited electrons and/or holes, they should be applicable to the devices for the solar-to-chemical energy conversion. On the other hand, TiO 2 itself can utilize only a small portion of solar energy because the material can absorb only ultraviolet light. The energy of ultraviolet light accounts for only 4 percent of the total solar energy at the sea level. Therefore, much attention is paid to narrow the bandgap of TiO 2 and to expand the photoabsorption spectrum into the visible-light region. 2)One of the effective ways to narrow the bandgap is the impurity doping. Especially, nitrogen should be an appropriate dopant because the ionic radius of nitrogen is close to that of oxygen and therefore it should be relatively easy to substitute oxygen with nitrogen.3) So far, several researches have revealed that nitrogen-doped TiO 2 shows photo-response under visiblelight irradiation both experimentally and theoretically.3)9) However, the photoabsorption rate at the visible-light region is not yet sufficiently improved in these studies. Therefore, more intense and detailed studies are needed to clarify the atomic geometries of dopants and the electronic structures of nitrogendoped TiO 2 .In the present work, we study the nitrogen-doping effects on the energetics and electronic properties of rutile, anatase, and brookite phases in heavily-doped cases within the framework of the density-functional theory. 10),11) First, we show the defect formation energies for the substitutional doping and discuss the structural properties of dopants. Next, we show the electronic properties of heavily nitrogen-doped TiO 2 with several different nitrogen concentrations.Our studies are based on the density-functional theory (DFT) within the framework of the local density approximation (LDA) using the Ceper...

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Density-Functional Theory of Excitation Spectra of Semiconductors: Application to Si

Cited by 252 publications

References 18 publications

Theory of quasiparticle energies: Band gaps and excitation spectra in solids

Theory of quasiparticle energies: Band gaps and excitation spectra in solids

Ab initiostudy of a mechanically gated molecule: From weak to strong correlation

Energetics and electronic properties of heavily nitrogen-doped titanium dioxide

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