Role of phonons and Coulomb interactions in fluctuating-valence europium compounds

1978 ◽  
Vol 18 (10) ◽  
pp. 5131-5139 ◽  
Author(s):  
O. L. T. de Menezes ◽  
A. Troper ◽  
A. A. Gomes
Keyword(s):  
Coulomb Interactions

Optical Properties of Cds Quantum Dots: The Key Role of the Spin-Orbit and Coulomb Interactions

1999 ◽  
Vol 571 ◽  
Author(s):  
M. Chamarro ◽  
V. Voliotis ◽  
M. Dib ◽  
T. Gacoin ◽  
C. Delerue ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Tight Binding ◽  
Spin Orbit ◽  
Coulomb Interactions ◽  
Electron Hole ◽  
Small Quantum ◽  
Cds Quantum Dot ◽  
Growth Method ◽  
Order Of Magnitude

ABSTRACTWe study theoretically and experimentally the effects of the Coulomb and the spin-orbit coupling on the electronic structure of small quantum dots. A tight-binding calculation with restricted configuration interaction is developed in a typical case: very small cubic quantum dots for which the electron-hole exchange interaction is of the order of magnitude of the spinorbit interaction. Experimentally, resonant photoluminescence and photoluminescence excitation are used to obtain information on a single size of CdS quantum dot obtained by a chemical growth method.

Role of the interparticle interactions and axial rotation in the massive white dwarfs theory

2018 ◽  
Vol 8 (1) ◽  
pp. 9-15
Author(s):  
D. Dzikovskyi ◽  
M. Vavrukh ◽  
S. Smerechynskyi
Keyword(s):  
Equilibrium Equation ◽  
White Dwarfs ◽  
Axial Rotation ◽  
Nuclear Model ◽  
Universal Functions ◽  
Coulomb Interactions ◽  
Interparticle Interactions ◽  
Loss Of Mass ◽  
Radial Variable

Using the equation of state of electron-nuclear model at high densities and the mechanical equilibrium equation we have investigated the influence of interparticle interactions and axial rotation on the macroscopic characteristics of massive white dwarfs. The method of solving the equilibrium equation in the case of rotation, using the basis of universal functions of the radial variable has been proposed. The conditions in which the axial rotation can compensate for weight loss of mass due to the interparticle Coulomb interactions have been established.

scholarly journals Электронная структура и квадрупольные взаимодействия в перспективных катодных материалах Na-=SUB=-x-=/SUB=-M-=SUB=-y-=/SUB=-(MoO-=SUB=-4-=/SUB=-)-=SUB=-3-=/SUB=-, M=Mn, Fe, Co и Ni

2019 ◽  
Vol 61 (5) ◽  
pp. 828
Author(s):  
Н.И. Медведева ◽  
А.В. Сердцев
Keyword(s):  
Density Functional ◽  
Resonance Method ◽  
Nuclear Magnetic Resonance Method ◽  
Coulomb Interactions ◽  
Functional Theory ◽  
Magnetic Resonance Method ◽  
The Density Functional Theory ◽  
Sodium Batteries ◽  
First Time

AbstractThe electronic structure and the magnetic properties of molybdates Na_ x M_ y (MoO_4)_3 (M = Mn, Fe, Co, and Ni) which are promising materials for sodium batteries have been studied in the framework of the density functional theory with the GGA and GGA+ U approximations for the first time. The calculations show that all the compounds are insulators. An important role of the correlation effects, provided by the on-site Coulomb interactions, was established in the formation of the band gap in these compounds. The quadrupole constants of  ^23Na nuclei are calculated in the nonmagnetic and ferromagnetic states within the GGA and GGA+ U approaches. It is shown that the quadrupole frequencies for nonequivalent crystallographic positions of sodium are in different frequency ranges, which allows to study the diffusion of sodium in these compounds by the Nuclear Magnetic Resonance method.

scholarly journals Activation of Water on MnOx-Modified Rutile (110) and Anatase (101) TiO2 and the Role of Cation Reduction

2018 ◽  
Author(s):  
Michael Nolan ◽  
Stephen Rhatigan
Keyword(s):  
Oxygen Vacancy ◽  
Light Absorption ◽  
Density Functional ◽  
Vacancy Formation ◽  
Visible Range ◽  
Coulomb Interactions ◽  
Carrier Recombination ◽  
Oxygen Vacancy Formation ◽  
Surface Hydroxyls

Surface modification of titania surfaces with dispersed metal oxide nanoclusters has the potential to enhance photocatalytic activity. These modifications can induce visible light absorption and suppress charge carrier recombination which are vital in improving the efficiency. We have studied heterostructures of Mn<sub>4</sub>O<sub>6</sub> nanoclusters modifying the TiO<sub>2</sub> rutile (110) and anatase (101) surfaces using density functional theory corrected for on-site Coulomb interactions (DFT + U). Such studies typically focus on the pristine surface, free of the point defects and surface hydroxyls present in real surfaces. In our study we have considered partial hydroxylation of the rutile and anatase surfaces and the role of cation reduction, via oxygen vacancy formation, and how this impacts on a variety of properties governing the photocatalytic performance such as nanocluster adsorption, light absorption, charge separation and reducibility. Our results indicate that the modifiers adsorb strongly at the surface and that modification extends light absorption into the visible range. MnO<sub>x</sub>-modified anatase can show an off-stoichiometric ground state, through oxygen vacancy formation and cation reduction spontaneously, and both modified rutile and anatase are highly reducible with moderate energy costs. Manganese ions are therefore present in a mixture of oxidation states. Photoexcited electrons and holes localize at cluster metal and oxygen sites, respectively. The interaction of water at the modified surfaces depends on the stoichiometry and spontaneous dissociation to surface bound hydroxyls is favoured in the presence of oxygen vacancies and reduced metal cations. Comparisons with bare TiO<sub>2</sub> and other TiO<sub>2</sub>-based photocatalyst materials are presented throughout.

scholarly journals Quantum capacitance and compressibility of graphene: The role of Coulomb interactions

2015 ◽  
Vol 91 (7) ◽  
Author(s):  
Yu. E. Lozovik ◽  
A. A. Sokolik ◽  
A. D. Zabolotskiy
Keyword(s):  
Quantum Capacitance ◽  
Coulomb Interactions

scholarly journals Comment on “The role of electron-electron interactions in two-dimensional Dirac fermions”

Science ◽  
2019 ◽  
Vol 366 (6470) ◽  
pp. eaav6869 ◽  
Author(s):  
S. Hesselmann ◽  
T. C. Lang ◽  
M. Schuler ◽  
S. Wessel ◽  
A. M. Läuchli
Keyword(s):  
Critical Point ◽  
Quantum Critical Point ◽  
Finite Size ◽  
Numerical Data ◽  
Research Articles ◽  
Fermi Velocity ◽  
Dirac Fermions ◽  
Two Dimensional ◽  
Coulomb Interactions

Tang et al. (Research Articles, 10 August 2018, p. 570) report on the properties of Dirac fermions with both on-site and Coulomb interactions. The substantial decrease, up to ~40%, of the Fermi velocity of Dirac fermions with on-site interaction is inconsistent with the numerical data near the Gross-Neveu quantum critical point. This results from an inappropriate finite-size extrapolation.

scholarly journals Modeling bound-to-continuum terahertz quantum cascade lasers: The role of Coulomb interactions

2010 ◽  
Vol 107 (1) ◽  
pp. 013104 ◽  
Author(s):  
Christian Jirauschek ◽  
Alpar Matyas ◽  
Paolo Lugli
Keyword(s):  
Quantum Cascade Lasers ◽  
Coulomb Interactions ◽  
Quantum Cascade ◽  
Cascade Lasers

BAND STRUCTURE AND ELECTRON VELOCITY MEASUREMENT IN CARBON NANOTUBES AND GRAPHENE

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2655-2664
Author(s):  
ROBIN J. NICHOLAS ◽  
KAI-CHIEH CHUANG
Keyword(s):  
Carbon Nanotubes ◽  
Band Structure ◽  
Cyclotron Resonance ◽  
Dirac Point ◽  
Electron Velocity ◽  
Coulomb Interactions ◽  
A Value ◽  
Number Of Layers ◽  
Structure Of Carbon Nanotubes

We discuss recent measurements of the interband spectrocopy of carbon nanotubes and studies of cyclotron resonance in graphene, using these to examine the possible dependence of the band structure of graphene on the number of layers present and the role of Coulomb interactions. Cyclotron resonances gives a value for the electron velocity at the Dirac point of 1.093×106 ms-1, which is ~ 20% larger than would be expected from deductions of the band structure of carbon nanotubes. In addition, a significant asymmetry exists between band structure for electrons and holes, which gives rise to a 5% difference between the velocities at energies of 125 meV away from the Dirac point.

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