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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 .
The critical point of quantum spin-on quantum Heisenberg films at hypercubic lattice points is studied by using the variational cumulative expansion method.From the analytical properties of free energy, we can calculate the critical reduction temperature θ (n) (l) to any cumulative expansion level n. The first three analytical expressions and numerical results of θ (n) (l) are given, and the results are analyzed and discussed.