混自旋σ=3/2和S=2与σ=3/2和S=5/2Ising系统基态性质的比较

Ground State Properties of Mixed Spin σ=3/2 and S=2 Ising System in Comparison with That of σ=3/2 and S=5/2 Ising System

研究了混自旋σ=3/2和S=2与混自旋σ=3/2和S=5/2两种Ising系统的基态性质.根据能量最低原理,通过比较各种可能基态构型的基态能,确定出了系统的基态相图.并得到了基态能Eg随DA/(zJ)和DB/(zJ)的变化规律.结果表明,对于混自旋σ=3/2和S=2 Ising系统可存在无序相,而对于混自旋σ=3/2和S=5/2 Ising系统只存在有序相.两种系统的基态能均随着DA/(zJ),DB/(zJ)值的变大而线性升高,但不同区域的斜率不同.DA/(zJ),DB/(zJ)值越大,基态能升高得越慢.此外发现对于混自旋σ=3/2和S=2 Ising系统存在4种构型共存点(0.5,0.5),而混自旋σ=3/2和S=5/2 Ising系统不存在4种构型共存点.

The ground state properties of mixed spin σ = 3/2 and S = 2 Ising system was studied comparatively with that of mixed spin σ = 3/2 and S = 5/2 Ising system. According to the principle of the lowest energy, the ground state phase diagram and ground state energy were obtained by comparing the ground state energy of various possible forms of ground states with each other. In the mixed spin σ = 3/2 and S = 2 Ising system there is no disordered phase, while in the mixed spin σ = 3/2 and S = 5/2 system only the ordered phase is found. The ground state energy of both systems increases linearly with the increasing values DA/（ zJ ） and DB/（ zJ ）, but the slopes are found not the same in different regions. The greater the values of DA/（ z J） and DB/（zJ）, the slower the increase in ground state energy. Furthermore, there is a concurrent point （0.5, 0.5） of four forms of ground states in the mixed spin σ = 3/2 and S = 2 Ising system, but the point is not found in the mixed spin σ = 3/2 and S = 5/2 system.