A discussion of mean –field theory in Ising spin models

IN this work an isospin system with spin values S = ±1 is studied through introducing improvement on a mean-field method for Ising spin system. The method is based on an extended Oguchi approximation (OA) . Within this scheme, three atoms are considered where the two nearest -neighbour spin correlation are taken into account when the Hamiltonian is presented .The result obtatined for the Curi temp. are more accurate compared with mean-field approximation (MFA) and Oguchi models Atable is stateed for comparison purposes , bet the present results and that of Curi temp. for approximation refeed earliear respectively