Mathematical model of ferromagnetism in statistical mechanics
Statistical mechanics
Thermodynamics
Kinetic theory
Particle statistics
Spin–statistics theorem
Indistinguishable particles
Maxwell–Boltzmann
Bose–Einstein
Fermi–Dirac
Parastatistics
Anyonic statistics
Braid statistics
Thermodynamic ensembles
NVE Microcanonical
NVT Canonical
µVT Grand canonical
NPH Isoenthalpic–isobaric
NPT Isothermal–isobaric
Models
Debye
Einstein
Ising
Potts
Potentials
Internal energy
Enthalpy
Helmholtz free energy
Gibbs free energy
Grand potential / Landau free energy
Scientists
Maxwell
Boltzmann
Bose
Gibbs
Einstein
Ehrenfest
von Neumann
Tolman
Debye
Fermi
v
t
e
The Ising model (or Lenz–Ising model), named after the physicists Ernst Ising and Wilhelm Lenz, is a mathematical model of ferromagnetism in statistical mechanics. The model consists of discrete variables that represent magnetic dipole moments of atomic "spins" that can be in one of two states (+1 or −1). The spins are arranged in a graph, usually a lattice (where the local structure repeats periodically in all directions), allowing each spin to interact with its neighbors. Neighboring spins that agree have a lower energy than those that disagree; the system tends to the lowest energy but heat disturbs this tendency, thus creating the possibility of different structural phases. The model allows the identification of phase transitions as a simplified model of reality. The two-dimensional square-lattice Ising model is one of the simplest statistical models to show a phase transition.[1]
The Ising model was invented by the physicist Wilhelm Lenz (1920), who gave it as a problem to his student Ernst Ising. The one-dimensional Ising model was solved by Ising (1925) alone in his 1924 thesis;[2] it has no phase transition. The two-dimensional square-lattice Ising model is much harder and was only given an analytic description much later, by Lars Onsager (1944). It is usually solved by a transfer-matrix method, although there exist different approaches, more related to quantum field theory.
In dimensions greater than four, the phase transition of the Ising model is described by mean-field theory. The Ising model for greater dimensions was also explored with respect to various tree topologies in the late 1970s, culminating in an exact solution of the zero-field, time-independent Barth (1981) model for closed Cayley trees of arbitrary branching ratio, and thereby, arbitrarily large dimensionality within tree branches. The solution to this model exhibited a new, unusual phase transition behavior, along with non-vanishing long-range and nearest-neighbor spin-spin correlations, deemed relevant to large neural networks as one of its possible applications.
The Ising problem without an external field can be equivalently formulated as a graph maximum cut (Max-Cut) problem that can be solved via combinatorial optimization.
^See Gallavotti (1999), Chapters VI-VII.
^Ernst Ising, Contribution to the Theory of Ferromagnetism
The Isingmodel (or Lenz–Isingmodel), named after the physicists Ernst Ising and Wilhelm Lenz, is a mathematical model of ferromagnetism in statistical...
the two-dimensional square lattice Isingmodel is a simple lattice model of interacting magnetic spins. The model is notable for having nontrivial interactions...
Ernst Ising (German: [ˈiːzɪŋ]; May 10, 1900 – May 11, 1998) was a German physicist, who is best remembered for the development of the Isingmodel. He was...
network (Isingmodel of a neural network or Ising–Lenz–Little model or Amari-Little-Hopfield network) is a spin glass system used to model neural networks...
physics is the relationship of the Isingmodel and the voting dynamics of a finite population. The Isingmodel, as a model of ferromagnetism, is represented...
electrons in the structure and here the Isingmodel can predict their behaviour with each other. This model is important for solving and understanding...
exponents of the ferromagnetic transition in the Isingmodel. In statistical physics, the Isingmodel is the simplest system exhibiting a continuous phase...
the Potts model, a generalization of the Isingmodel, is a model of interacting spins on a crystalline lattice. By studying the Potts model, one may gain...
are treated quantum mechanically. It is related to the prototypical Isingmodel, where at each site of a lattice, a spin σ i ∈ { ± 1 } {\displaystyle...
learning models include support-vector machines, clustering and probabilistic graphical models. Moreover, due to its close connection to Isingmodels, QUBO...
tensor operator).[citation needed] The critical Isingmodel is the critical point of the Isingmodel on a hypercubic lattice in two or three dimensions...
solutions in some interacting model systems. A classic example of this is the Isingmodel, which is a widely discussed toy model for the phenomena of ferromagnetism...
the Isingmodel is a mathematical method to prove results. In applied mathematics, the construction of an irreducible Markov Chain in the Isingmodel is...
statistics, econometrics, and signal processing, an autoregressive (AR) model is a representation of a type of random process; as such, it is used to...
etc. the random cluster model is a random graph that generalizes and unifies the Isingmodel, Potts model, and percolation model. It is used to study random...
anisotropic) next-nearest neighbor Isingmodel, usually known as the ANNNI model, is a variant of the Isingmodel. In the ANNNI model, competing ferromagnetic and...
1D Isingmodel, which is already solved by Ising himself. He then computed the transfer matrix of the "Ising ladder", meaning two 1D Isingmodels side-by-side...
dimensions or when exact solutions are known such as the two-dimensional Isingmodel. The theoretical treatment in generic dimensions requires the renormalization...
Hence the critical β of the XY model cannot be smaller than the double of the critical temperature of the Isingmodel β c X Y ≥ 2 β c I s {\displaystyle...
the Isingmodel lattice. So this anomalous dimension in the conformal field theory is the same as a particular critical exponent of the Isingmodel phase...
the Landau theory, which is identical to the mean field theory for the Isingmodel, the value of the upper critical dimension comes out to be 4. If the...
Sherrington–Kirkpatrick model with external field or stochastic Ising–Lenz–Little model), named after Ludwig Boltzmann is a stochastic spin-glass model with an external...
networks had precursors in the Isingmodel due to Wilhelm Lenz (1920) and Ernst Ising (1925), though the Isingmodel conceived by them did not involve...