Hubbard-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>U</mml:mi></mml:math>calculations for Cu from first-principle Wannier functions

Schnell, I.; Czycholl, Gerd; Albers, R. C.

doi:10.1103/physrevb.65.075103

Cited by 134 publications

(64 citation statements)

References 33 publications

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“…24,25,33 Recent ab initio studies of the bare and the screened Coulomb interaction in 3d transition metals focused only on the NM state. 48,56,[61][62][63][64][65][66] Here we present a detailed study of the matrix elements in the MLWF basis for the proper FM state of the 3d transition metals Fe, Co, and Ni. For comparison with previous works the NM states of these three elements and the rest of the 3d series are considered, too.…”

Section: Matrix Elements Of the Coulomb Potentialmentioning

confidence: 99%

Wannier-function approach to spin excitations in solids

et al. 2010

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We present a computational scheme to study spin excitations in magnetic materials from first principles. The central quantity is the transverse spin susceptibility, from which the complete excitation spectrum, including single-particle spin-flip Stoner excitations and collective spin-wave modes, can be obtained. The susceptibility is derived from many-body perturbation theory and includes dynamic correlation through a summation over ladder diagrams that describe the coupling of electrons and holes with opposite spins. In contrast to earlier studies, we do not use a model potential with adjustable parameters for the electron-hole interaction but employ the random-phase approximation. To reduce the numerical cost for the calculation of the four-point scattering matrix we perform a projection onto maximally localized Wannier functions, which allows us to truncate the matrix efficiently by exploiting the short spatial range of electronic correlation in the partially filled d or f orbitals. Our implementation is based on the full-potential linearized augmented-plane-wave method. Starting from a ground-state calculation within the local-spin-density approximation ͑LSDA͒, we first analyze the matrix elements of the screened Coulomb potential in the Wannier basis for the 3d transition-metal series. In particular, we discuss the differences between a constrained nonmagnetic and a proper spin-polarized treatment for the ferromagnets Fe, Co, and Ni. The spectrum of single-particle and collective spin excitations in fcc Ni is then studied in detail. The calculated spin-wave dispersion is in good overall agreement with experimental data and contains both an acoustic and an optical branch for intermediate wave vectors along the ͓1 0 0͔ direction. In addition, we find evidence for a similar double-peak structure in the spectral function along the ͓1 1 1͔ direction. To investigate the influence of static correlation we finally consider LSDA+ U as an alternative starting point and show that, together with an improved description of the Fermi surface, it yields a more accurate quantitative value for the spin-wave stiffness constant, which is overestimated in the LSDA.

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Section: Matrix Elements Of the Coulomb Potentialmentioning

confidence: 99%

Wannier-function approach to spin excitations in solids

et al. 2010

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“…Therefore, one has to choose a gauge Ψ kα → e iφ(k) Ψ kα which leads to localized Wannier functions [26,27]. The substitution [28] …”

Section: B Plane-wave Expansionmentioning

confidence: 99%

Superfluid drag of two-species Bose-Einstein condensates in optical lattices

Hofer

Bruder²,

Stojanović³

2012

Phys. Rev. A

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We study two-species Bose-Einstein condensates in quasi two-dimensional optical lattices of varying geometry and potential depth. Based on the numerically exact Bloch and Wannier functions obtained using the plane-wave expansion method, we quantify the drag (entrainment coupling) between the condensate components. This drag originates from the (short range) interspecies interaction and increases with the kinetic energy. As a result of the interplay between interaction and kinetic energy effects, the superfluid-drag coefficient shows a non-monotonic dependence on the lattice depth. To make contact with future experiments, we quantitatively investigate the drag for mass ratios corresponding to relevant atomic species.

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“…For the simulation of the mean-field potential we neglect the overlap of neighbor orbitals; the approach is equivalent to two-center treatment of the Coulomb integrals 47 . Accordingly, the contribution of the j− th orbital to the spin density at l-th ion is given by |c lj p z (r − r j )| 2 , and…”

Section: Theorymentioning

confidence: 99%

Charging graphene nanoribbon quantum dots

Żebrowski

Szafran²

2015

Phys. Rev. B

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We describe charging a quantum dot induced electrostatically within a semiconducting graphene nanoribbon by electrons or holes. The applied model is based on a tight-binding approach with the electron-electron interaction introduced by a mean field local spin density approximation. The numerical approach accounts for the charge of all the pz electrons and screening of external potentials by states near the charge neutrality point. Both a homogenous ribbon and a graphene flake embedded within the ribbon are discussed. The formation of transport gaps as functions of the external confinement potential (top gate potential) and the Fermi energy (back gate potential) are described in good qualitative agreement with the experimental data. For a fixed number of excess electrons we find that the excess charge added to the system is, -depending on the voltages defining the work point of the device: i) delocalized outside the quantum dot -in the transport gap due to the top gate potential ii) localized inside the quantum dot -in the transport gap due to the back gate potential or iii) extended over both the quantum dot area and the ribbon connections -outside the transport gaps. The applicability of the frozen valence band approximation to describe charging the quantum dot by excess electrons is also discussed.

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Hubbard-Ucalculations for Cu from first-principle Wannier functions

Cited by 134 publications

References 33 publications

Wannier-function approach to spin excitations in solids

Wannier-function approach to spin excitations in solids

Superfluid drag of two-species Bose-Einstein condensates in optical lattices

Charging graphene nanoribbon quantum dots

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