一维铁磁海森堡模型的热力学性质
Thermodynamic Properties of One-Dimensional Ferromagnetic Heisenberg Model

利用修正的自旋波理论研究有次近邻相互作用的一维自旋为1/2的铁磁海森堡模型. 通过自洽方法，得到次近邻相互作用对系统的热力学性质的影响. 结果表明，当存在次近邻相互作用时，体系比热的最大值及其对应位置分别是温度的指数和线性函数关系. 当比热取最大值时，磁化率、内能及自由能均为次近邻相互作用的递减线性函数. 而熵是次近邻相互作用的递减指数函数. 在不存在次近邻相互作用时，其结果与Bethe Ansatz精确解相符合.
： The modified spin-wave method is applied to the one-dimensional spin-1/2 ferromagnetic Heinsenberg model with next-nearest neighbor interaction. The influence of the next-nearest neighbor interaction on the thermodynamic properties of the system is obtained within the self-consistent method. The exponential and linear laws which are induced by next-nearest neighbor interaction are found for heights and positions of maximum of the specific heat, respectively. At positions of the specific heat maximum, the magnetic susceptibility, as well as the internal energy and free energy, exhibits the linear decrease with the next-nearest neighbor interaction. But the entropy has an exponential decrease. The results agree with the Bethe Ansatz data in the case without next-nearest neighbor interaction