Free exchange-correlation energy of electron quantum wire in dynamical mean-field approximation

2019 ◽  
Author(s):  
Kulveer Kaur ◽  
Akariti Sharma ◽  
Vinayak Garg ◽  
R. K. Moudgil
Keyword(s):  
Quantum Wire ◽  
Correlation Energy ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Exchange Correlation ◽  
Electron Quantum

Free exchange-correlation energy of an electron quantum wire

2018 ◽  
Author(s):  
Akariti Sharma ◽  
Kulveer Kaur ◽  
Vinayak Garg ◽  
R. K. Moudgil
Keyword(s):  
Quantum Wire ◽  
Correlation Energy ◽  
Exchange Correlation ◽  
Electron Quantum

scholarly journals Theoretical Band and Confinement Interpretation of 1D Electrons: Impact on Plasmons and Exchange-Correlation Functionals

2021 ◽  
Author(s):  
Akariti Sharma
Keyword(s):  
Ad Hoc ◽  
Mean Field ◽  
Energy Shift ◽  
Field Approximation ◽  
Quantitative Agreement ◽  
Mean Field Approximation ◽  
Local Exchange ◽  
Spin Orbital ◽  
Exchange Correlation ◽  
Density Response Function

Abstract Theoretical band and confinement interpretation of electron gas in lowest energy sub-band of quasi- 1D metallic wire have been done. Counter effects have been investigated on electrostatic oscillations (plasmons) determined by the electron density response function. Carrier correlations are treated by incorporating the local exchange-correlation (XC) effects within mean- field approximation. Results obtained are in quantitative agreement with experiments data of Nagao et al. (2006 Phys. Rev. Lett. 97 116802). Variation in both degeneracy and confinement potential cause a clear energy- shift in the electrostatic oscillations accomplished by asymmetry in band effective mass. Resultant massasymmetry is attributed to the greater strength of XC- effects. These contributions turns out to be quite logical in describing the splitting of 1D-bands over ad-hoc spin-orbital splitting idea of Nagao et al. Calculated XC-functionals agreed well with the lattice regularized diffusion Monte Carlo (LRDMC) simulation data (2006 Phys. Rev. B 74, 245427, 2009 J. Phys. A:Math.Theor.42 214021). Competition among XC-functionals and kinetic energy tendencies decides a criterion by satisfying which a metallic quasi-1D wire may undergo an instability at certain critical temperature (Tc).

scholarly journals Bosonic collective excitations in Fermi gases

2020 ◽  
pp. 2060009
Author(s):  
Niels Benedikter
Keyword(s):  
Correlation Energy ◽  
Weak Interactions ◽  
Random Phase ◽  
Mean Field ◽  
Quantum Correlations ◽  
Field Approximation ◽  
Collective Excitations ◽  
Mean Field Approximation ◽  
Effective Theory ◽  
Hartree Fock

Hartree–Fock theory has been justified as a mean-field approximation for fermionic systems. However, it suffers from some defects in predicting physical properties, making necessary a theory of quantum correlations. Recently, bosonization of many-body correlations has been rigorously justified as an upper bound on the correlation energy at high density with weak interactions. We review the bosonic approximation, deriving an effective Hamiltonian. We then show that for systems with Coulomb interaction this effective theory predicts collective excitations (plasmons) in accordance with the random phase approximation of Bohm and Pines, and with experimental observation.

The Determination of the Magnetoelectric Coupling Coefficient in Ferroelectric–Ferromagnetic Composite Based on PZT–Ferrite

2013 ◽  
Vol 58 (4) ◽  
pp. 1401-1403 ◽  
Author(s):  
J.A. Bartkowska ◽  
R. Zachariasz ◽  
D. Bochenek ◽  
J. Ilczuk
Keyword(s):  
Dielectric Permittivity ◽  
Coupling Coefficient ◽  
Mean Field ◽  
Field Approximation ◽  
Theoretical Description ◽  
Magnetoelectric Coupling ◽  
Mean Field Approximation ◽  
Dielectric Measurements ◽  
Temperature Dependences ◽  
Multiferroic Composite

Abstract In the present work, the magnetoelectric coupling coefficient, from the temperature dependences of the dielectric permittivity for the multiferroic composite was determined. The research material was ferroelectric-ferromagnetic composite on the based PZT and ferrite. We investigated the temperature dependences of the dielectric permittivity (") for the different frequency of measurement’s field. From the dielectric measurements we determined the temperature of phase transition from ferroelectric to paraelectric phase. For the theoretical description of the temperature dependence of the dielectric constant, the Hamiltonian of Alcantara, Gehring and Janssen was used. To investigate the dielectric properties of the multiferroic composite this Hamiltonian was expressed under the mean-field approximation. Based on dielectric measurements and theoretical considerations, the values of the magnetoelectric coupling coefficient were specified.

scholarly journals Hexagonal-Shaped Spin Crossover Nanoparticles Studied by Ising-Like Model Solved by Local Mean Field Approximation

2021 ◽  
Vol 7 (5) ◽  
pp. 69
Author(s):  
Catherine Cazelles ◽  
Jorge Linares ◽  
Mamadou Ndiaye ◽  
Pierre-Richard Dahoo ◽  
Kamel Boukheddaden
Keyword(s):  
Spin Crossover ◽  
Hexagonal Lattice ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Ligand Field ◽  
Order And Disorder ◽  
The Matrix ◽  
Local Mean ◽  
Parameter Values

The properties of spin crossover (SCO) nanoparticles were studied for five 2D hexagonal lattice structures of increasing sizes embedded in a matrix, thus affecting the thermal properties of the SCO region. These effects were modeled using the Ising-like model in the framework of local mean field approximation (LMFA). The systematic combined effect of the different types of couplings, consisting of (i) bulk short- and long-range interactions and (ii) edge and corner interactions at the surface mediated by the matrix environment, were investigated by using parameter values typical of SCO complexes. Gradual two and three hysteretic transition curves from the LS to HS states were obtained. The results were interpreted in terms of the competition between the structure-dependent order and disorder temperatures (TO.D.) of internal coupling origin and the ligand field-dependent equilibrium temperatures (Teq) of external origin.

Geometrical and Transport Properties of Disordered Fibre Networks: Analytical Results

1997 ◽  
Vol 11 (20) ◽  
pp. 867-875 ◽  
Author(s):  
A. A. Rodríaguez ◽  
E. Medina
Keyword(s):  
Probability Distribution ◽  
Transport Properties ◽  
Geometrical Structure ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Fracture Networks ◽  
Simplified Models ◽  
Fibre Density ◽  
Line Network

We study novel geometrical and transport properties of a 2D model of disordered fibre networks. To assess the geometrical structure we determine, analytically, the probability distribution for the number of fibre intersections and resulting segment sizes in the network as a function of fibre density and length. We also determine, numerically, the probability distribution of pore perimeters and areas. We find a non-monotonous behavior of the perimeter distribution whose main features can be explained by solving for two simplified models of the line network. Finally we formulate a mean field approximation to conduction, above the percolation threshold, using the derived results. Relevance of the results to fracture networks will be discussed.

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