On some problems of analysis of isotropic antiferromagnets

An equivalent Hamiltonian method for the analysis of isotropic antiferromagnets is proposed. The Hamiltonian does not contain the terms corresponding to the processes of non-conservation of spin waves and gives the possibility to perform the calculations with a limited and controlled error. The high as well as the low temperature analysis of the system was carried out with the help of the equivalent Hamiltonian. Some results are compared with those of the u−v transformation method.