On the connections and differences among three mean-field approximations: a stringent test

2017 ◽  
Vol 19 (28) ◽  
pp. 18514-18518 ◽  
Author(s):  
Shasha Yi ◽  
Cong Pan ◽  
Liming Hu ◽  
Zhonghan Hu
Keyword(s):  
Mean Field ◽  
One Dimensional ◽  
Stringent Test ◽  
The Mean ◽  
Mean Field Approximations

Using the left–right symmetry in one-dimensional systems, the mean field idea can be implemented to yield accurate structure corrections.

MEAN FIELD APPROACH TO THE GAP OF A MODEL INTERACTING SYSTEM

1988 ◽  
Vol 02 (01) ◽  
pp. 87-101
Author(s):  
KAJOLI BANERJEE ◽  
VIJAY A. SINGH ◽  
G. R. BHAT
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Mean Field ◽  
Functional Theory ◽  
One Dimensional ◽  
Coulomb Term ◽  
The Density Functional Theory ◽  
The Mean ◽  
Transfer Term ◽  
Mean Field Approximations

The well-known local density approximation severely underestimates the gap of insulating materials. We undertake a study of an infinite one-dimensional model interacting system where the gap is known exactly. We use variational procedures, similar in spirit to Hohenberg and Kohn's derivation of the density functional theory. The mean field approximations so obtained are used to calculate the gap in the eigenspectrum. The gap is found to be systematically underestimated for realistic values of the parameters (u/t ≤ 4 where u is the Coulomb term and t, the transfer term). For u/t > 4, the approximate gap is in close agreement with the exact gap. The underestimation of the gap is investigated with respect to the discontinuity in the effective potential.

Uniqueness and Symmetry for the Mean Field Equation on Arbitrary Flat Tori

2020 ◽  
Author(s):  
Guangze Gu ◽  
Changfeng Gui ◽  
Yeyao Hu ◽  
Qinfeng Li
Keyword(s):  
Field Equation ◽  
Level Sets ◽  
Mean Field ◽  
Flat Torus ◽  
One Dimensional ◽  
Uniqueness Of The Solution ◽  
Flat Tori ◽  
The Mean ◽  
Symmetry Result ◽  
Mean Field Equation

Abstract We study the following mean field equation on a flat torus $T:=\mathbb{C}/(\mathbb{Z}+\mathbb{Z}\tau )$: $$\begin{equation*} \varDelta u + \rho \left(\frac{e^{u}}{\int_{T}e^u}-\frac{1}{|T|}\right)=0, \end{equation*}$$where $ \tau \in \mathbb{C}, \mbox{Im}\ \tau>0$, and $|T|$ denotes the total area of the torus. We first prove that the solutions are evenly symmetric about any critical point of $u$ provided that $\rho \leq 8\pi $. Based on this crucial symmetry result, we are able to establish further the uniqueness of the solution if $\rho \leq \min{\{8\pi ,\lambda _1(T)|T|\}}$. Furthermore, we also classify all one-dimensional solutions by showing that the level sets must be closed geodesics.

scholarly journals The 1/N-expansion as a perturbation about the mean field theory: A one-dimensional fermi model

1996 ◽  
Vol 179 (3) ◽  
pp. 623-646 ◽  
Author(s):  
D. H. U. Marchetti ◽  
P. A. Faria da Veiga ◽  
T. R. Hurd
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Fermi Model ◽  
One Dimensional ◽  
The Mean

COLLAPSE OF K-Rb FERMI-BOSE MIXTURES IN OPTICAL LATTICES

2006 ◽  
Vol 20 (30n31) ◽  
pp. 5199-5203
Author(s):  
D. M. JEZEK ◽  
H. M. CATALDO
Keyword(s):  
Low Temperature ◽  
Optical Lattice ◽  
Optical Lattices ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
One Dimensional ◽  
Different Types ◽  
The Mean ◽  
Number Of Particles

We study a confined mixture of Rb and K atoms in a one dimensional optical lattice, at low temperature, in the quanta1 degeneracy regime. This mixture exhibits an attractive boson-fermion interaction, and thus above certain values of the number of particles the mixture collapses. We investigate, in the mean-field approximation, the curve for which this phenomenon occurs, in the space of number of particles of both species. This is done for different types of optical lattices.

scholarly journals RELAXATION UNDER OUTFLOW DYNAMICS WITH RANDOM SEQUENTIAL UPDATING

2005 ◽  
Vol 16 (11) ◽  
pp. 1771-1783 ◽  
Author(s):  
SYLWIA KRUPA ◽  
KATARZYNA SZNAJD-WERON
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Mean Field ◽  
Square Lattice ◽  
One Dimensional ◽  
Sequential Updating ◽  
The Mean

In this paper we compare the relaxation in several versions of the Sznajd model (SM) with random sequential updating on the chain and square lattice. We start by reviewing briefly all proposed one-dimensional versions of SM. Next, we compare the results obtained from Monte Carlo simulations with the mean field results obtained by Slanina and Lavicka. Finally, we investigate the relaxation on the square lattice and compare two generalizations of SM, one suggested by Stauffer et al. and another by Galam. We show that there are no qualitative differences between these two approaches, although the relaxation within the Galam rule is faster than within the well known Stauffer et al. rule.

FRÖHLICH'S ONE-DIMENSIONAL SUPERCONDUCTOR WITH PARA-FERMI STATISTICS

1994 ◽  
Vol 08 (19) ◽  
pp. 1195-1200 ◽  
Author(s):  
V. L. SAFONOV ◽  
A. V. ROZHKOV
Keyword(s):  
Density Wave ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Wave State ◽  
One Dimensional ◽  
Fermi Statistics ◽  
The Mean ◽  
A Charge ◽  
Dimensional Crystal

The hypothesis that conduction electrons in a one-dimensional crystal obey para-Fermi statistics is discussed. Thermal properties of Fröhlich's model in the mean-field approximation are calculated within the framework of this hypothesis. It is shown that the temperature of the phase transition to a charge density wave state is greater in a system with parastatistics.

NOTE ON ANALYTICAL STUDIES OF ONE-DIMENSIONAL HOLOGRAPHIC SUPERCONDUCTORS

2012 ◽  
Vol 27 (02) ◽  
pp. 1250001 ◽  
Author(s):  
RAN LI
Keyword(s):  
Equations Of Motion ◽  
Mean Field ◽  
Study Phase ◽  
Coupling Term ◽  
Analytical Treatment ◽  
One Dimensional ◽  
Holographic Superconductors ◽  
Scalar Operator ◽  
Sturm Liouville ◽  
The Mean

We employ the variational method for the Sturm–Liouville eigenvalue problem to analytically study phase transition of one-dimensional holographic superconductors. It is shown that this method is not a very powerful method to analytically calculate the properties of holographic superconductors. From the analytical treatment of scalar operator condensate at critical temperature, we also show that the mean-field critical exponent 1/2 results from the coupling term between scalar field and vector field, which may be an universal property of holographic superconductors with a similar coupling term in their equations of motion.

scholarly journals Impurities in a one-dimensional Bose gas: the flow equation approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fabian Brauneis ◽  
Hans-Werner Hammer ◽  
Mikhail Lemeshko ◽  
Artem Volosniev
Keyword(s):  
Mean Field ◽  
Interaction Strength ◽  
Field Approximation ◽  
Flow Equation ◽  
Mean Field Approximation ◽  
Bose Gases ◽  
One Dimensional ◽  
Flow Equations ◽  
Impurity Interaction ◽  
The Mean

A few years ago, flow equations were introduced as a technique for calculating the ground-state energies of cold Bose gases with and without impurities[1,2]. In this paper, we extend this approach to compute observables other than the energy. As an example, we calculate the densities, and phase fluctuations of one-dimensional Bose gases with one and two impurities. For a single mobile impurity, we use flow equations to validate the mean-field results obtained upon the Lee-Low-Pines transformation. We show that the mean-field approximation is accurate for all values of the boson-impurity interaction strength as long as the phase coherence length is much larger than the healing length of the condensate. For two static impurities, we calculate impurity-impurity interactions induced by the Bose gas. We find that leading order perturbation theory fails when boson-impurity interactions are stronger than boson-boson interactions. The mean-field approximation reproduces the flow equation results for all values of the boson-impurity interaction strength as long as boson-boson interactions are weak.

scholarly journals ONE DIMENSIONAL ASYNCHRONOUS COOPERATIVE PARRONDO'S GAMES

2003 ◽  
Vol 03 (04) ◽  
pp. L389-L398 ◽  
Author(s):  
ZORAN MIHAILOVIĆ ◽  
MILAN RAJKOVIĆ
Keyword(s):  
Computer Simulation ◽  
Markov Chain ◽  
Discrete Time ◽  
Transition Probabilities ◽  
Mean Field ◽  
Discrete Time Markov Chain ◽  
One Dimensional ◽  
Field Approach ◽  
The Mean ◽  
The One

A discrete-time Markov chain solution with exact rules for general computation of transition probabilities of the one-dimensional cooperative Parrondo's games is presented. We show that winning and the occurrence of the paradox depends on the number of players. Analytical results are compared to the results of the computer simulation and to the results based on the mean-field approach.

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