共查询到20条相似文献,搜索用时 31 毫秒
1.
《Physica A》1995,214(3):452-460
We propose a general method by which an Ising spin of a spin-S Ising model is decomposed into Ising spins less than S. Some exactly solvable spin-S Ising models with S greater than 1/2 are obtained without using Horiguchi's condition or its extended conditions. These systems are reduced to the Ising model of spin ± 1 or an Ashkin-Teller model. 相似文献
2.
The anisotropic two-layer Ising model is studied by the phenomenological renormalization group method. It is found that the anisotropic two-layer Ising model with symmetric couplings belongs to the same universality class as the two dimensional Ising model.Received: 2 March 2003, Published online: 11 August 2003PACS:
05.50.+q Lattice theory and statistics (Ising, Potts, etc.) -
02.70.-c Computational techniques 相似文献
3.
4.
We solve the spin-1 quantum Ising model with single-ion anisotropy by mapping it onto a series of segmented spin-1/2 transverse Ising chains, separated by the S(z)=0 states called holes. A recursion formula is derived for the partition function to simplify the summation of hole configurations. This allows the thermodynamic quantities of this model to be rigorously determined in the thermodynamic limit. The low temperature behavior is governed by the interplay between the hole excitations and the fermionic excitations within each spin-1/2 Ising segment. The quantum critical fluctuations around the Ising critical point of the transverse Ising model are strongly suppressed by the hole excitations. 相似文献
5.
The phase transition in squaric acid is discussed on the basis of three-dimensionally coupled Ising chains, where the protons in the hydrogen bonds serve as the Ising spins. The Ising model is solved in an approximation treating the chains exactly and the interactions between them in mean-field approximation. 相似文献
6.
We present an efficient algorithm for calculating the properties of Ising models in two dimensions, directly in the spin basis, without the need for mapping to fermion or dimer models. The algorithm computes the partition function and correlation functions at a single temperature on any planar network of N Ising spins in O(N;{3/2}) time or less. The method can handle continuous or discrete bond disorder and is especially efficient in the case of bond or site dilution, where it executes in O(NlnN) time near the percolation threshold. We demonstrate its feasibility on the ferromagnetic Ising model and the +/-J random-bond Ising model and discuss the regime of applicability in cases of full frustration such as the Ising antiferromagnet on a triangular lattice. 相似文献
7.
S. Kobe 《Journal of statistical physics》1997,88(3-4):991-995
The Ising model is one of the standard models in statistical physics. Since 1969 more than 13800 publications using this model have appeared. In 1997 Ernst Ising celebrated his 97th birthday. Some biographical notes and milestones of the development of the Ising model are given. 相似文献
8.
Jerzy Cis?o 《Physica A》2008,387(26):6535-6537
We present a innovative relationship between ground states of the Ising model and dimer coverings which sheds new light on the Ising models with highly degenerate ground states and enables one to construct such models. Thanks to this relationship we also find the generating function for dimers as the appropriate limit of the free energy per spin for the Ising model. 相似文献
9.
The High Temperature Ising Model on the Triangular Lattice is a Critical Bernoulli Percolation Model
We define a new percolation model by generalising the FK representation of the Ising model, and show that on the triangular
lattice and at high temperatures, the critical point in the new model corresponds to the Ising model. Since the new model
can be viewed as Bernoulli percolation on a random graph, our result makes an explicit connection between Ising percolation
and critical Bernoulli percolation, and gives a new justification of the conjecture that the high temperature Ising model
on the triangular lattice is in the same universality class as Bernoulli percolation. 相似文献
10.
Richard C. Brower K. J. M. Moriarty Peter Orland Pablo Tamayo 《Journal of statistical physics》1990,58(1-2):141-157
We introduce a lattice gas for particles with discrete momenta (1, 0, –1) and local deterministic microdynamics, which exactly reproduces Creutz's microcanonical algorithm for the ferromagnetic Ising model. However, because of the manifest gauge invariance of our variables, both the Ising ferromagnetic and spin-glass systems share precisely the same dynamics with different initial conditions. Additional conservation laws in the 1D Ising case result in a completely integrable system in the limit of zero or unbounded demon energy cutoff. Numerical investigations of ergodicity are presented for the pure Ising lattice gas in one and two dimensions. 相似文献
11.
S Ramasesha 《Pramana》1984,23(6):745-749
Based on the analogy between polytypes and spin-half Ising chains, polytypes can be considered as different phases of a spin-half
Ising system with competing nearest neighbour and next nearest neighbour interactions operating in a single direction. It
is known that such an Ising system exhibits extremely rich and complicated phase behaviour. This behaviour is shown to be
very similar to the phase behaviour exhibited by polytypes. 相似文献
12.
《Physics letters. A》2006,349(6):505-508
A star-triangle mapping transformation is used to establish an exact correspondence between the spin-1/2 Ising model on the Shastry–Sutherland (orthogonal-dimer) lattice and respectively, the spin-1/2 Ising model on a bathroom tile (4–8) lattice. Exact results for the critical temperature and spontaneous magnetization are obtained and compared with corresponding results on the regular Ising lattices. 相似文献
13.
R. Costa-Santos 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(1):85-90
We discuss a geometrical interpretation of the Z-invariant Ising model in terms of isoradial embeddings of planar lattices.
The Z-invariant Ising model can be defined on an arbitrary planar lattice if and only if certain paths on the lattice edges
do not intersect each other more than once or self-intersect. This topological constraint is equivalent to the existence of
isoradial embeddings of the lattice. Such embeddings are characterized by angles which can be related to the model coupling
constants in the spirit of Baxter's geometrical solution. The Ising model on isoradial embeddings studied recently by several
authors in the context of discrete holomorphy corresponds to the critical point of this particular Z-invariant Ising model. 相似文献
14.
Ferromagnetic Ising models on the lattice Sierpinski gasket are considered. We prove the Dobrushin-Shlosmann mixing condition and discuss corresponding properties of the stochastic Ising models. 相似文献
15.
A transverse Ising model for a magnetic superlattice of spin-1/2 Ising layered media intercalated by periodic interfaces described by the spin-1/2 Ising model is considered. Phase diagrams and different profiles of magnetization determined by the parameters of the model are discussed within a variational procedure based on Bogoliubov's inequality for the free energy. Our results agree to those of the other's work at the limit of Ω = 0. 相似文献
16.
《Nuclear Physics B》1986,265(1):92-112
We investigate the continuum limit of the Ising model on a 2-dimensional random lattice using Monte Carlo and strong coupling techniques. No evidence is found for deviation from the behaviour of the standard Ising model on a regular lattice; we do not see the modified critical properties found in the bond-diluted Ising model. Our results suggest that the continuum limit is the usual non-interacting Majorana fermion theory. 相似文献
17.
C. Itzykson 《Nuclear Physics B》1982,210(4):448-476
We review the fermionization of the two-dimensional Ising model and its applications. This is the first part of a series devoted to Ising like systems. 相似文献
18.
K. Konishi L. B. Le N. Hara 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(5):1-6
We propose the mapping of polynomial of degree 2S constructed as a linear combination of powers of spin-S (for simplicity, we called as spin-S polynomial) onto spin-crossover state. The spin-S polynomial in general can be projected onto non-symmetric degenerated spin up (high-spin) and spin down (low-spin) momenta. The total number of mapping for each general spin-S is given by 2(22S ? 1). As an application of this mapping, we consider a general non-bilinear spin-S Ising model which can be transformed onto spin-crossover described by Wajnflasz model. Using a further transformation we obtain the partition function of the effective spin-1/2 Ising model, making a suitable mapping the non-symmetric contribution leads us to a spin-1/2 Ising model with a fixed external magnetic field, which in general cannot be solved exactly. However, for a particular case of non-bilinear spin-S Ising model could become equivalent to an exactly solvable Ising model. The transformed Ising model exhibits a residual entropy, then it should be understood also as a frustrated spin model, due to competing parameters coupling of the non-bilinear spin-S Ising model. 相似文献
19.
Hailin Huang 《International Journal of Theoretical Physics》2009,48(12):3491-3497
The entanglement and optimal dense coding at entangled states of a 1D Ising chain in the presence of an external magnetic
field with an arbitrary direction, are investigated. The entanglement concurrence and the optimal dense coding capacity are
calculated for different orientations of the magnetic field. It has been found that the direction of external magnetic field
has effects on the entanglement concurrence and optimal dense coding capacity. In the case of antiferromagnet, the quantum
phase transition occurs when an external magnetic field is parallel to Ising orientation. The concurrence increases when the
angle between the direction of magnetic field and Ising orientation become smaller at ground state in certain parameter regimes,
so does the optimal dense coding. The maximum moves toward the direction perpendicular to the Ising orientation in higher
temperature. In contrast, the more concurrence and optimal dense coding can be produced only in the case of an external magnetic
field perpendicular to Ising orientation at zero and low temperature for ferromagnetic case. 相似文献
20.
GAO Xing-Ru YANG Zhan-Ru 《理论物理通讯》2007,48(3):553-562
In this paper we propose an Ising model on an infinite ladder lattice, which is made of two infinite Ising spin chains with interactions. It is essentially a quasi-one-dimessional Ising model because the length of the ladder lattice is infinite, while its width is finite. We investigate the phase transition and dynamic behavior of Ising model on this quasi-one-dimessional system. We use the generalized transfer matrix method to investigate the phase transition of the system. It is found that there is no nonzero temperature phase transition in this system. At the same time, we are interested in Glauber dynamics. Based on that, we obtain the time evolution of the local spin magnetization by exactly solving a set of master equations. 相似文献