中国物理B ›› 2004, Vol. 13 ›› Issue (7): 1124-1128.doi: 10.1088/1009-1963/13/7/028
崔晓波1, 陈芝得2
Cui Xiao-Bo (崔晓波)a, Chen Zhi-De (陈芝得)b
摘要: We present the calculation and comparison of tunnel splitting at excited levels of biaxial spin models by various methods, including the generalized instanton method, the generalized path integral method for coherent spin states, the perturbation method, and the exact method by numerical diagonalization of the Hamiltonian. It is found that, for integer spin with spin number around 10, tunnel splitting predicted by the generalized path integral for coherent spin states is about 10^{-n} times of the exact numerical result for the nth excited level, while the ratio of the results of the perturbation method and the exact numerical method diverges in the large spin limit. We thus conclude that the generalized instanton method is the best approximate way for calculating tunnel splitting in spin models.
中图分类号: (Excited states: methodology)