(1) 平均场近似(Mean-Field Approximation) 平均场近似基于以下思想:对spin间交互作用简化, 令所有格点对间具有相同的交互作用 J , 并于使用平均场 m 以及关于格点 i的扰动项 δσi 对格点 i 所关联的参数σi使用σi=⟨σi⟩−δσi=m−δσi进行表现。 基于该表现,并于忽略二次扰动项(例如 δ...
而对于平均场近似(Mean Field Approximation,简称MFA)所得的磁化强度可以表达为: ,(1-33) 其中q是最近邻自旋的数目,对于二维正方晶格来说q=4。 图1.5严格解与平均场近似所得二维Ising模型磁化强度的比较。 在图1.5中,与平均场近似所得的解(TC=4K)相比,严格解(TC=2.269K)有着更低的临界温度TC,而且磁化强度...
Cooperative phenomena are introduced via the simple Ising model in which spins having two states occupy a lattice and interact with nearest neighbors and an applied magnetic field. We study this model in the mean field approximation. Correlations among spin states are neglected, so each spin intera...
lattice is calculated using the recently proposed transfer-matrix version of a mean-field approximation. For two-layered case, the present results (Tc/J = 3.20755(5) and 3.62279(2) for the open and periodic boundary conditions, respectively) improve considerably on the previous estimation obtained...
11、而对于平均场近似(Mean Field Approximation,简称MFA)所得的磁化强度可以表达为:,(1-33)其中q是最近邻自旋的数目,对于二维正方晶格来说q=4。图1.5 严格解与平均场近似所得二维Ising模型磁化强度的比较。在图1.5中,与平均场近似所得的解(TC=4K)相比,严格解(TC=2.269K)有着更低的临界温度TC,而且磁化强度...
Gulpinar investigated the critical behavior of ultrasound wave absorption coefficient in the metamagnetic Ising model within the mean-field approximation [38]. Acoustic Signatures of the Phases and Phase Transitions in the Blume Capel Model with Random Crystal Field Here we use a quantum simulator comp...
We study the thermodynamic limit of the algebraic dynamics for an "almost" mean-field Ising model, which is a slight generalization of the Ising model in the mean-field approximation. We prove that there exists a family of relevant" states on which the algebraic dynamics α t can be defined...
The dynamics of non-equilibrium Ising model with parallel updates is investigated using a generalized mean field approximation that incorporates multiple two-site correlations at any two time steps, which can be obtained recursively. The proposed method shows significant improvement in predicting local sy...
A spin-1 Ising model, which simulates the thermodynamic behavior of He-Hemixtures along the λ line and near the critical mixing point, is introduced and solved in the mean-field approximation. For reasonable values of the parameters of the model the phase diagram is qualitatively similar to ...
Ising modelmolecular compoundsmean-field approximationSome transition-metal containing molecules can undergo a spin transition (ST) between a low-spin (LS) ... H Bolvin,O Kahn - 《Chemical Physics》 被引量: 82发表: 1995年 Phase diagram of an Ising model for ultrathin magnetic films We study...