A generalized spin-1 Blume-Capel model with distance/volume dependent nearest-neighbor exchange interaction is introduced and investigated using the standard methods of statistical mechanics. Besides of the volume-dependent magnetic energy, the static electromagnetic energy and anharmonic Einstein phonon contribution are also taken into account. Taking the simple volume dependence of all energy contributions we have obtained the equation of state, magnetic moment, internal and Helmholtz free energy of the system. The ground-state and finite- temperature phase diagrams are obtained and discussed in detail. Is it shown that the generalized spin-1 Blume-Capel model exhibits a novel critical behavior appearing due to magnetostriction and thermal volume variations. The presented approach is very universal and easily applicable to many other theoretical models in different fields of solid state physics.

中文翻译：

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具有距离相关的最近邻交换相互作用和磁弹性耦合的自旋 1 Blume-Capel 模型的新临界行为

使用统计力学的标准方法介绍并研究了具有距离/体积相关的最近邻交换相互作用的广义自旋 1 Blume-Capel 模型。除了与体积相关的磁能外，还考虑了静态电磁能和非谐爱因斯坦声子贡献。考虑所有能量贡献的简单体积依赖性，我们得到了系统的状态方程、磁矩、内部和亥姆霍兹自由能。获得并详细讨论了基态和有限温度相图。是否表明广义自旋 1 Blume-Capel 模型表现出由于磁致伸缩和热体积变化而出现的新临界行为。