“Majority Representation” of Alloy Electronic States

Wang, L.-W.; Bellaïche, L.; Wei, Su‐Huai; Zunger, Alex

doi:10.1103/physrevlett.80.4725

Cited by 116 publications

(101 citation statements)

References 21 publications

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“…This Green function can be obtained numerically by using the Lanczos recursive method. 15,16,[23][24][25] To numerically obtain an exact ensemble-averaged Green's function near the Dirac point, a large lattice containing millions sites (4800 × 4800) is used. The large samples guarantee that the calculated Green's function is free from the finite size errors.…”

mentioning

confidence: 99%

Vacancy-induced splitting of the Dirac nodal point in graphene

Zhu

Shi

et al. 2012

Phys. Rev. B

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We investigate the vacancy effects on quasiparticle band structure of graphene near the Dirac point. It is found that each Dirac nodal point splits into two new nodal points due to the coherent multiple scattering among vacancies. The energy split between the two nodal points is proportional to the square root of vacancy concentration. In addition, an extra dispersionless band is developed at zero energy. Our theory offers an excellent explanation to the recent experiments. Electronic properties of materials are often determined by their low-energy excitations. The low-energy excitations of pristine grapheme form the Dirac nodal structures centered at two inequivalent corners K and K of the first Brillouin zone with linear energy dispersion.1,2 The common belief is that the Dirac nodal structure is robust against the shortranged potential scattering because long electron wavelength near the Dirac nodal point would not be able to "see such scatters." 3 However, recent progress in the classical wave physics demonstrates that local resonant structures can dramatically modify waves whose wavelengths are several orders of magnitude larger than the structure sizes. [4][5][6] Vacancies as well as various chemical adsorbates in graphene can create resonant states in the vicinity of the Dirac point. Thus, similar to the classical wave, one expects that electronic structures and transport properties of graphene near the Dirac nodal point can be dramatically modified by vacancies. Indeed, the angleresolved photoemission spectroscopy (ARPES) indicates the opening of a tunable band gap near the Dirac point and the formation of a dispersionless band in hydrogenated quasi-freestanding graphene. 7,8 Another study of hydrogenated graphene on SiC showed signals of a metal-to-insulator transition (MIT) due to the electron localization.9 Away from the charge neutrality point, the transport measurements demonstrated a sublinear carrier dependence of the conductivity.10 Within the Boltzmann transport framework and the assumption of existence of the Dirac nodal structure, theoretical prediction agrees with the experimental observation.11 However, it fails to explain the transport behavior near the nodal point, showing the breakdown of Boltzmann transport theory there. 12,13 In fact, both experiments 7,8 and numerical simulations 14,15 suggest that the Dirac nodal structure is significantly changed by the resonant scattering. Therefore, the discrepancy between the theoretical prediction and transport measurements may arise from the change of quasiparticle behavior near the nodal point, and a deep understanding of the resonant scattering effects is needed.In this Brief Report, we study the effects of the vacancy resonant scattering on Dirac nodal structure in graphene. The quasiparticle dispersion relation is extracted from the spectral function A(k,E), which can be calculated by extending the well-developed Lanczos approach. 16 In contrast to the previous theoretical studies of the spectral function by the average T-matrix approximatio...

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confidence: 99%

Vacancy-induced splitting of the Dirac nodal point in graphene

Zhu

Shi

et al. 2012

Phys. Rev. B

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“…The most successful approach that links the supercell band structure with the primitive basis representation is based on a Bloch spectral density [3,4], which is also known as a "spectral weight" [5][6][7]. The spectral weight w n (k) amounts to a Bloch k-character of the n'th energy eigenstates ǫ n and fulfills the normalization k w n (k) = 1.…”

Section: Introductionmentioning

confidence: 99%

“…The spectral weight can be obtained by a Fourier transformation of local basis functions, such as atomic orbitals [6,8,9], Wannier functions [10][11][12][13][14][15][16][17] or projected local orbitals [18]. In the case of a non-local basis set, such as plane waves, the spectral weight can be constructed from the Fourier expansion coefficients by gathering them in groups associated with a particular Bloch wave vector [2,7,[19][20][21]. The latter approach is the most straightforward for implementation in solid-state ab initio electronic structure codes, since the plane wave (PW) expansion coefficients are readily available in pseudopotential or full-potential packages.…”

Section: Introductionmentioning

confidence: 99%

Unfolding the band structure of disordered solids: From bound states to high-mobility Kane fermions

et al. 2014

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Supercells are often used in ab initio calculations to model compound alloys, surfaces and defects. One of the main challenges of supercell electronic structure calculations is to recover the Bloch character of electronic eigenstates perturbed by disorder. Here we apply the spectral weight approach to unfolding the electronic structure of group III-V and II-VI semiconductor solid solutions. The illustrative examples include: formation of donor-like states in dilute Ga(PN) and associated enhancement of its optical activity, direct observation of the valence band anticrossing in dilute GaAs:Bi, and a topological band crossover in ternary (HgCd)Te alloy accompanied by emergence of high-mobility Kane fermions. The analysis facilitates interpretation of optical and transport characteristics of alloys that are otherwise ambiguous in traditional first-principles supercell calculations.

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“…Several methods have been developed and successfully applied to the unfolding of eigenfunctions and electronic band structures. 67,[112][113][114][115][116][117][118][119][120][121] In this section, we present the common ground of all these methods, and we discuss the contributions of this thesis to the field.…”

Section: Brillouin Zone Folding and Unfolding 33mentioning

confidence: 99%

Electronic properties of complex interfaces and nanostructures

Medeiros

2015

Linköping Studies in Science and Technology. Dissertations

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To my grandmother, minha veinha. AbstractThis thesis investigates the structural and electronic properties of graphene, polyaromatic hydrocarbon (PAH) molecules, and other carbon-based materials, when interacting with metallic surfaces, as well as under the influence of different types of perturbations. Density functional theory, incorporating van der Waals interactions, has been employed.PAH molecules can, with gradual accuracy, be considered as approximations to an infinite graphene layer. A method to estimate the contributions to the binding energies and net charge transfers from different types of carbon atoms and CH groups in graphene-and PAH-metal systems has been generalized. In this extended method, the number and the nature of the functional groups is determined using a first-principles approach, rather than intuitively or through empirical considerations. Relationships between charge transfers, interface dipole moments and work functions in such systems are explored.Although the electronic structure of physisorbed graphene keeps most of the features of freestanding graphene, the use of large supercells in calculations makes it difficult to resolve the changes introduced in the band structures of such materials. In this thesis, this was the initial motivation for the development of a method to perform the Brillouin zone unfolding of band structures. This method, as initially developed, is shown to be of general use for any periodic structure, and is even further generalized -through the introduction of the unfolding density operator -to tackle the unfolding of the eigenvalues of any arbitrary operator, with both scalar as well as spinor eigenstates.A combined experimental and theoretical investigation of the self-assembly of a binary mixture of 4,9-diaminoperylene-quinone-3,10-diimine (DPDI) and 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) molecules on Ag(111) is presented. The DFT calculations performed here allow for the investigation of the interplay between molecule-molecule and molecule-surface interactions in the network.Besides the main results mentioned above, this thesis also incorporates a study of silicon-metal nanostructures, as well as an investigation of the use of hybrid v vi graphene-graphane structures as prototypes for atomically precise design in nanoelectronics. Populärvetenskaplig sammanfattningI denna avhandling undersöks strukturella och elektroniska egenskaper hos grafen, polycykliska aromatiska kolväten (PAH) och andra kolbaserade material, i situationer då dessa växelverkar med metallytor eller utsätts för olika slags störningar. Undersökningarna är baserade på s.k. täthetsfunktionalteori (DFT) och tar hänsyn till van der Waals-interaktioner.Polycykliska aromatiska kolväten kan, med gradvis noggrannhet, anses representera grafen med oändlig utsträckning. I avhandlingen har en metod för att uppskatta bidragen till bindningsenergier och laddningsöverföringar från olika kolatomer hos grafen-och PAH-metallsystem generaliserats på ett sådant sätt att antalet och karakt...

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“Majority Representation” of Alloy Electronic States

Cited by 116 publications

References 21 publications

Vacancy-induced splitting of the Dirac nodal point in graphene

Vacancy-induced splitting of the Dirac nodal point in graphene

Unfolding the band structure of disordered solids: From bound states to high-mobility Kane fermions

Electronic properties of complex interfaces and nanostructures

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