scholarly journals Phase transitions of antiferromagnetic Ising spins on the zigzag surface of an asymmetrical Husimi lattice

2019 ◽  
Vol 6 (3) ◽  
pp. 181500 ◽  
Author(s):  
Ran Huang ◽  
Purushottam D. Gujrati
Keyword(s):  
Phase Transitions ◽  
Ising Model ◽  
Spontaneous Magnetization ◽  
Square Lattice ◽  
Two Dimensional ◽  
Simple Formulation ◽  
First Order ◽  
Husimi Lattice ◽  
Antiferromagnetic Ising Model ◽  
Ising Spins

An asymmetrical two-dimensional Ising model with a zigzag surface, created by diagonally cutting a regular square lattice, has been developed to investigate the thermodynamics and phase transitions on surface by the methodology of recursive lattice, which we have previously applied to study polymers near a surface. The model retains the advantages of simple formulation and exact calculation of the conventional Bethe-like lattices. An antiferromagnetic Ising model is solved on the surface of this lattice to evaluate thermal properties such as free energy, energy density and entropy, from which we have successfully identified a first-order order–disorder transition other than the spontaneous magnetization, and a secondary transition on the supercooled state indicated by the Kauzmann paradox.

RANDOMLY DECORATED ISING MODEL

1991 ◽  
Vol 05 (04) ◽  
pp. 675-683 ◽  
Author(s):  
L.L. GONÇALVES
Keyword(s):  
Phase Diagram ◽  
Ising Model ◽  
Exchange Interaction ◽  
Discrete Distribution ◽  
Square Lattice ◽  
Two Dimensional ◽  
Percolation Thresholds ◽  
Ising Spins

A study of the two-dimensional (square lattice) randomly decorated Ising model is presented. The bonds are decorated with Ising spins of magnitude s and an annealed discrete distribution [Formula: see text] for the exchange interaction of the decorating bonds is considered. The phase diagram is exactly obtained and for the case where competition is present there are two percolation thresholds, namely, [Formula: see text] which are independent of s. Reentrant behaviour is presented by the system and the region in the space parameters where it occurs is discussed.

scholarly journals Anisotropic scaling of the two-dimensional Ising model II: surfaces and boundary fields

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Hendrik Hobrecht ◽  
Fred Hucht
Keyword(s):  
Ising Model ◽  
Boundary Conditions ◽  
Scaling Limit ◽  
Finite Size ◽  
Square Lattice ◽  
Conformal Field ◽  
Anisotropic Scaling ◽  
Finite Lattices ◽  
Antiferromagnetic Ising Model ◽  
Boundary Fields

Based on the results published recently [SciPost Phys. 7, 026 (2019)], the influence of surfaces and boundary fields are calculated for the ferromagnetic anisotropic square lattice Ising model on finite lattices as well as in the finite-size scaling limit. Starting with the open cylinder, we independently apply boundary fields on both sides which can be either homogeneous or staggered, representing different combinations of boundary conditions. We confirm several predictions from scaling theory, conformal field theory and renormalisation group theory: we explicitly show that anisotropic couplings enter the scaling functions through a generalised aspect ratio, and demonstrate that open and staggered boundary conditions are asymptotically equal in the scaling regime. Furthermore, we examine the emergence of the surface tension due to one antiperiodic boundary in the system in the presence of symmetry breaking boundary fields, again for finite systems as well as in the scaling limit. Finally, we extend our results to the antiferromagnetic Ising model.

scholarly journals Neural Network for Prediction of Curie Temperature of Two-Dimensional Ising Model

2021 ◽  
Vol 21 (1) ◽  
pp. 51-60
Author(s):  
A.O. Korol ◽  
◽  
V.Yu. Kapitan ◽  
◽  
◽  
...  
Keyword(s):  
Neural Network ◽  
Ising Model ◽  
Curie Temperature ◽  
High Temperature Phase ◽  
Square Lattice ◽  
Temperature Phase ◽  
The Neural Network ◽  
Different Temperatures ◽  
Low Temperature Phase ◽  
Ising Spins

The authors describe a method for determining the critical point of a second-order phase transitions using a convolutional neural network based on the Ising model on a square lattice. Data for training were obtained using Metropolis algorithm for different temperatures. The neural network was trained on the data corresponding to the low-temperature phase, that is a ferromagnetic one and high-temperature phase, that is a paramagnetic one, respectively. After training, the neural network analyzed input data from the entire temperature range: from 0.1 to 5.0 (in dimensionless units) and determined (the Curie temperature T_c). The accuracy of the obtained results was estimated relative to the Onsager solution for a flat lattice of Ising spins.

THE SIMULATION OF 2D SPIN-1 ISING MODEL WITH POSITIVE BIQUADRATIC INTERACTION ON A CELLULAR AUTOMATON

2003 ◽  
Vol 14 (10) ◽  
pp. 1305-1320 ◽  
Author(s):  
BÜLENT KUTLU
Keyword(s):  
Phase Transition ◽  
Ising Model ◽  
Cellular Automaton ◽  
Intermediate Phase ◽  
Finite Size ◽  
Square Lattice ◽  
Two Dimensional ◽  
Finite Size Scaling ◽  
Creutz Cellular Automaton ◽  
Antiferromagnetic Spin

The two-dimensional antiferromagnetic spin-1 Ising model with positive biquadratic interaction is simulated on a cellular automaton which based on the Creutz cellular automaton for square lattice. Phase diagrams characterizing phase transition of the model are presented for a comparison with those obtained from other calculations. We confirm the existence of the intermediate phase observed in previous works for some values of J/K and D/K. The values of the static critical exponents (β, γ and ν) are estimated within the framework of the finite-size scaling theory for D/K<2J/K. Although the results are compatible with the universal Ising critical behavior in the region of D/K<2J/K-4, the model does not exhibit any universal behavior in the interval 2J/K-4<D/K<2J/K.

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