Unfolding spinor wave functions and expectation values of general operators: Introducing the unfolding-density operator

Medeiros, Paulo V. C.; Tsirkin, Stepan S.; Stafström, Sven; Björk, Jonas

doi:10.1103/physrevb.91.041116

Cited by 325 publications

(241 citation statements)

References 32 publications

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“…The band structure of the supercell containing one N was unfolded to the primitive cell band structure using the BandUP code. 38,39 All the calculations included spin-orbit coupling, which, for bulk InSb gives a spin-orbit valence band split off of 800 meV, in good agreement with experiment (803 meV). 40 The N fraction was determined for epilayers grown at temperatures between 270 and 365 C using a fixed growth rate of 0.5 lm h…”

supporting

confidence: 66%

Band gap reduction in InNxSb1-x alloys: Optical absorption, k · P modeling, and density functional theory

Linhart

Rajpalke

Buckeridge

et al. 2016

Applied Physics Letters

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Using infrared absorption, the room temperature band gap of InSb is found to reduce from 174 (7.1 μm) to 85 meV (14.6 μm) upon incorporation of up to 1.13% N, a reduction of ∼79 meV/%N. The experimentally observed band gap reduction in molecular-beam epitaxial InNSb thin films is reproduced by a five band k · P band anticrossing model incorporating a nitrogen level, EN, 0.75 eV above the valence band maximum of the host InSb and an interaction coupling matrix element between the host conduction band and the N level of β = 1.80 eV. This observation is consistent with the presented results from hybrid density functional theory.

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supporting

confidence: 66%

Band gap reduction in InNxSb1-x alloys: Optical absorption, k · P modeling, and density functional theory

Linhart

Rajpalke

Buckeridge

et al. 2016

Applied Physics Letters

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“…Similar to the S = 2 ground state as discussed above, the electronic structure of the competing S = 3/2 spin state is also found to be half-metallic within all theoretical descriptions of exchange-correlation functional employed here, and shown for U Cr = 4eV in Figure 6. Note that the Note that the electronic band structures for the supercells are calculated using the band unfolding technique implemented in the BandUP code [55,56]. For a supercell, the band structure calculation results in zone folding of bands due to the contraction of corresponding Brillouin zone, which makes the identification of impurity states from the host bands difficult.…”

Section: Discussionmentioning

confidence: 99%

Engineering the Kondo state in two-dimensional semiconducting phosphorene

Babar

Kabir

2018

Phys. Rev. B

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Correlated interaction between dilute localized impurity electrons with the itinerant host conduction electrons in metals gives rise to the conventional many-body Kondo effect below sufficiently low temperature. In sharp contrast to these conventional Kondo systems, we report an intrinsic, robust and high-temperature Kondo state in two-dimensional semiconducting phosphorene. While absorbed at a thermodynamically stable lattice defect, Cr impurity triggers an electronic phase transition in phosphorene to provide conduction electrons, which strongly interact with the localized moment generated at the Cr site. These manifests into intrinsic Kondo state, where the impurity moment is quenched at multi-stage and at temperatures in the 40-200 K range. Further, along with a much smaller extension of Kondo cloud, the predicted Kondo state is shown to be robust under uniaxial strain and layer thickness, which greatly simplifies its future experimental realization. We predict the present study will open up new avenues in Kondo physics and trigger further theoretical and experimental studies.

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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%

“…It can potentially lead to major difficulties when analyzing data obtained using imperfect SCs, as the simulated systems cannot be reduced to smaller PCs even though, in many cases, a description in terms of the PCBZs might still be physically reasonable. 67,112 The folding, however, occurs even for perfect SCs, for which the calculated properties are entirely…”

mentioning

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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Unfolding spinor wave functions and expectation values of general operators: Introducing the unfolding-density operator

Cited by 325 publications

References 32 publications

Band gap reduction in InNxSb1-x alloys: Optical absorption, k · P modeling, and density functional theory

Band gap reduction in InNxSb1-x alloys: Optical absorption, k · P modeling, and density functional theory

Engineering the Kondo state in two-dimensional semiconducting phosphorene

Electronic properties of complex interfaces and nanostructures

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