The spin-pair correlation functions are calculated for the Ising model with nearest-neighbor interaction J>0 and next-nearest-neighbor interaction J′ on the square lattice in terms of three approximations of the simplified cluster variation method with strip clusters as the basic clusters. The critical indices λ, ν and ην are estimated from the obtained spin-pair correlation functions with the aid of the coherent-anomaly method. For J′/J < -0.5, we confirm that the system belongs to the Onsager universality class in the sense of the weak universality hypothesis.
|Number of pages||18|
|Journal||Physica A: Statistical Mechanics and its Applications|
|Publication status||Published - 1993 Feb 1|
ASJC Scopus subject areas
- Statistics and Probability
- Condensed Matter Physics