“…The antiferromagnetic isotropic spin-1 model introduced by Affleck, Kennedy, Lieb and Tasaki (AKLT model) [3], whose ground state can be exactly calculated, has been a useful toy model to validate Haldane's prediction of the massive behavior for integer spin chains. Moreover, it lead to a deeper understanding for integer spin chains such as the discovery of the special type of long-range order [4,5]. The AKLT model has been generalized to higher-spin models, anisotropic models, etc [6,7,8,9,10,11,12,13,14,15,16,17].…”