【摘要】 采用变分累积展开法研究了超立方格点上任意自旋的量子Heisenberg薄膜的临界点 .从自由能的解析性质出发 ,原则上能计算作为多层膜层数l函数的临界约化温度θ(n) (l)到任意累积展开级次n.给出了θ(n)(l)的前三级解析表达式和数值结果 ,并对结果作了分析和讨论 .更多还原

【Abstract】 The quantum Heisenberg hyperfilm is studied by the variational\|cumulant expansion method. From the analytic properties of free energy, the critical reduced temperature θ\-c(l) can in principle be calculated to any order cumulant expansion as a function of the number l of hyperlayers in hyperfilm. Explicit expressions for θ\-c(l) up to the third order are giren for various lattices and spins. The numberical results are given and discussed.更多还原