Low-Temperature Series Expansions for the Square-Lattice Ising Model with First and Second Neighbour Interactions

Syh-Fu Lee；Keh-Ying Lin

Chinese Journal of Physics

34卷5期（1996 / 10 / 01）

1261 - 1269

英文

We have calculated the low-temperature series expansions of the spontaneous magnetization and susceptibility of the square-lattice Ising model with first and second neighbour interactions to the 24th and 20th order respectively. We use the Pad& approximants to estimate the critical exponents and find that 0.122 ＜β ＜ 0.128 and 1.70 ＜ γ' ＜ 1.85. Our results are consistent with the universality hypothesis which predicts that square-lattice Ising models with interactions beyond first neighbours have the same critical exponents β = 0.125 and γ' = 1.75.