Search results for "Charge Density"

showing 10 items of 206 documents

Broken symmetries in the reconstruction of ν=1 quantum Hall edges

1999

Spin-polarized reconstruction of the v=1 quantum Hall edge is accompanied by a spatial modulation of the charge density along the edge. We find that this is also the case for finite quantum Hall droplets: current spin density functional calculations show that the so-called Chamon-Wen edge forms a ring of apparently localized electrons around the maximum density droplet (MDD). The boundaries of these different phases qualitatively agree with recent experiments. For very soft confinement, Chern-Simons Ginzburg-Landau theory indicates formation of a non-translational invariant edge with vortices (holes) trapped in the edge region.

PhysicsCondensed Matter - Mesoscale and Nanoscale PhysicsCondensed matter physicsFOS: Physical sciencesCharge densityElectronInvariant (physics)Quantum Hall effectCondensed Matter PhysicsAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic MaterialsVortexMesoscale and Nanoscale Physics (cond-mat.mes-hall)Homogeneous spaceMaximum densitySpin densityPhysica E: Low-dimensional Systems and Nanostructures
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Quantum Dots in Magnetic Fields: Phase Diagram and Broken Symmetry at the Maximum-Density-Droplet Edge

1999

Quantum dots in magnetic fields are studied within the current spin-density-functional formalism avoiding any spatial symmetry restrictions of the solutions. We find that the maximum-density droplet reconstructs into states with broken internal symmetry: The Chamon-Wen edge coexists with a modulation of the charge density along the edge. The phase boundaries between the polarization transition, the maximum-density droplet, and its reconstruction are in agreement with recent experimental results.

PhysicsCondensed matter physicsInternal symmetryQuantum dotGeneral Physics and AstronomyCharge densityMaximum densitySymmetry breakingPolarization (waves)Magnetic fieldPhase diagram
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Background charge fluctuations in SET-transistors

1996

We have studied fluctuations of background charges in single electron tunnelling (SET) transistors. Changes in the charge distribution of the substrate and other dielectric materials near the transistor cause uncontrolled changes in its conductivity. We have observed big differences in the type and frequency of the conductivity fluctuations between different samples, but no systematic dependence on the substrate material has been found. To obtain information about the location of the source of the charge noise, we performed coincidence measurements on two separate SET transistors which were made very near to each other. The results suggest that the conductivity fluctuations are caused by ch…

PhysicsCondensed matter physicsTransistorGeneral Physics and AstronomyCharge densityCharge (physics)Substrate (electronics)DielectricConductivityCondensed Matter::Mesoscopic Systems and Quantum Hall EffectNoise (electronics)law.inventionlawTunnel junctionAtomic physics
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Spatial fluctuations of the chemical potential in case of nearly coherent transport along an ordered chain

1991

The Landauer-Buttiker approach is used to describe electron transport along a chain of scatterers which allow elastic as well as inelastic processes. The inelastic scattering takes place via side branches coupling the chain to electron reservoirs which serve as a heat bath. For small inelastic coupling of the scatterers to the heat bath strong interference effects lead to spatial fluctuations of the charge density. The corresponding oscillations of the chemical potential are discussed in view of phase-sensitive experiments measuring the four-probe resistance.

PhysicsCouplingElastic scatteringCondensed matter physicsOscillationCharge densityGeneral Materials ScienceElectronInelastic scatteringCondensed Matter PhysicsElectron transport chainTransfer matrixElectronic Optical and Magnetic MaterialsZeitschrift f�r Physik B Condensed Matter
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Solvent Effects on Electronically Excited States Using the Conductor-Like Screening Model and the Second-Order Correlated Method ADC(2).

2015

The conductor-like screening model (COSMO) is used to treat solvent effects on excited states within a correlated method based on the algebraic-diagrammatic construction through second-order ADC(2). The origin of solvent effects is revisited, and it is pointed out that two types of contributions have to be considered. One effect is due to the change of the solute's charge distribution after excitation, which triggers a reorganization of the solvent. Initially, only the electronic degrees of freedom adapt to the new charge distribution (nonequilibrium case); for sufficiently long-lived states, the reorientation of the solvent molecules contributes, as well (equilibrium case). The second effe…

PhysicsCouplingQuantitative Biology::BiomoleculesCharge densityNon-equilibrium thermodynamicsNanotechnologyChromophoreComputer Science ApplicationsCondensed Matter::Soft Condensed MatterSolventChemical physicsExcited statePhysics::Chemical PhysicsPhysical and Theoretical ChemistrySolvent effectsExcitationJournal of chemical theory and computation
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Relativistic Corrections and Unitary Equivalence

1992

Model calculations of the charge and quadrupole deuteron form factors were performed starting from a class of approximately unitary equivalent Hamiltonians and using consistent charge density operators. The approximate unitary equivalence was tested numerically and found to break down already for rather small values of momentum transfer.

PhysicsDeuteriumMomentum transferQuadrupoleCharge densityUnitary stateEquivalence (measure theory)Mathematical physics
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A new algorithm for simulating flows of conducting fluids in the presence of electric fields

2012

Abstract We propose an algorithm based on dissipative particle dynamics (DPD) for simulations of conducting fluids in the presence of an electric field. In this model, the electrostatic equations are solved in each DPD time step to determine the charge density at the fluid surfaces. These surface charges are distributed on a thin layer of fluid particles near the interface, and the corresponding interfacial electric forces are added to other DPD forces. The algorithm is applied to the electrospinning process at the Taylor cone formation stage. It is shown that, when the applied voltage is sufficiently high, the algorithm captures the formation of a Taylor cone with analytical apex angle 98.…

PhysicsDissipative particle dynamicsGeneral Physics and AstronomyCharge densityElectrospinningTaylor conePhysics::Fluid DynamicsCondensed Matter::Soft Condensed MatterHardware and ArchitectureElectric fieldSurface chargeBoundary value problemAlgorithmVoltageComputer Physics Communications
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Quantum dots in magnetic fields: Unrestricted symmetries in the current spin-density functional formalism

1999

We apply the current spin-density functional formalism (CSDFT) of Vignale and Rasolt to two-dimensional quantum dots in magnetic fields. Avoiding any spatial symmetry restrictions of the solutions, we find that a broken rotational symmetry of the electronic charge density can occur in high magnetic fields.

PhysicsFormalism (philosophy of mathematics)Condensed matter physicsQuantum dotQuantum mechanicsHomogeneous spaceRotational symmetryTime-dependent density functional theoryElectronic charge densitySpin densityAtomic and Molecular Physics and OpticsMagnetic fieldThe European Physical Journal D
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Sudden change in the nuclear charge distribution of very light gold isotopes

1987

4 pages, 3 tables, 2 figures.-- PACS nrs.: 21.10.Ft, 21.10.Ky, 27.70.+q.

PhysicsGeneral Physics and AstronomyCharge densityRadiusPhotoionizationEffective nuclear chargeTime of flight[PACS] Electromagnetic momentsIonization[PACS] Charge distribution150 ≤ A ≤ 189 [[PACS] Properties of specific nuclei listed by mass ranges]Nuclear Physics - ExperimentPhysics::Atomic PhysicsIsotopes of gold[PACS] Properties of specific nuclei listed by mass ranges:150 ≤ A ≤ 189Atomic physicsHyperfine structure
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Diffusivity in force-free simulations of global magnetospheres

2021

Abstract: Assuming that the numerical diffusivity triggered by violations of the force-free electrodynamics constraints is a proxy for the physical resistivity, we examine its impact on the overall dynamics of force-free aligned pulsar magnetospheres endowed with an equatorial current sheet. We assess the constraint violations as a diffusivity source. The effects of modifications on electric fields used to restore force-free conditions are not confined to the equatorial current sheet, but modify the magnetospheric dynamics on timescales shorter than the pulsar rotational period. These corrections propagate especially via a channel that was unexplored, namely, changes induced to the electric…

PhysicsHigh Energy Astrophysical Phenomena (astro-ph.HE)Astrophysics::High Energy Astrophysical PhenomenaFluxCharge densityFOS: Physical sciencesAstronomy and AstrophysicsThermal diffusivityLuminositysymbols.namesakeCurrent sheetMaxwell's equationsPulsarSpace and Planetary ScienceQuantum electrodynamicsPoynting vectorsymbolsAstrophysics - High Energy Astrophysical PhenomenaAstrophysics - Instrumentation and Methods for AstrophysicsInstrumentation and Methods for Astrophysics (astro-ph.IM)
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