Disorder and size effects in the envelope-function approximation

Dargam, T. G.; Capaz, Rodrigo B.; Koiller, Belita

doi:10.1103/physrevb.56.9625

Cited by 47 publications

(48 citation statements)

References 6 publications

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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%

“…In the ultimate extreme of spatially localized states, the uncertainty approaches its fundamental limit of ∆k ∼ r −1 B , where r B is the localization radius. 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].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

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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“…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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“…One can also characterize the donor ground state by its orbital averaged spectral weight 17 Fig. 2͑b͒ as a function of U 0 .…”

Section: ͑1͒mentioning

confidence: 99%

“…The overall charge distribution is conveniently described through the TB envelope function squared, 17 ͉⌿ EF ͑R i ͉͒ 2 = ͚ ͉a i ͉ 2 .…”

mentioning

confidence: 99%