一种具有铁磁与反铁磁相互作用Ising模型的热力学性质

对最近邻自旋间具有反铁磁相互作用Ｊ_s，相隔偶数个自旋间又具有指数型长程铁磁相互作用Ｊ₁的一维Ｉｓｉｎｇ模型，利用积分方程的方法得出内能和比热的解析表达式。在Ｊ₁＝１，Ｊ_s分别为０．０５，０．１和０．３的条件下，作出零场时的内能和比热随温度参量变化的图形，并指出其相变临界点。在Ｊ₁＝１，Ｊ_s＝０．１的条件下，作出外磁场变化对内能和比热的影响图。鉴于系统在低温、零场或弱场以及较弱关键词：

THERMODYNAMICAL BEHAVIOR OF THE ISING MODEL WITH FERROMAGNETIC AND ANTI-FERROMAGNETIC INTERACTIONS

Using the integral equation method, we have got the analytic expressions of the internal energy and specific heat for the one-dimensional Ising model with nearest-neighbour antiferromagnetic repulsion J_s and infinitely long-range exponential (Kae-Helfand-type) ferromagnetic attraction J₁ acting only on even-numbered neighbours. Under the conditions of J₁=1 and J_s being 0.05, 0.1 and 0.3 respectively, we have drawn the curves of the internal energy and specific heat varying with temperature in zero external magnetic field, and pointed out its critical phase transition point. Under the conditions of J₁=1,J_s=0.1, we have drawn the curves of influence of the external magnetic field upon the internal energy and specific heat. Because there exist double solutions for the system under low temperatures, zero or weak external magnetic field and weaker antiferromagnetic interactions, it is inferred that there should exist another quasi-stable state of the model under the given conditions.