A study of the Heisenberg model by means of the COM is reported in Ref. . In particular the following properties have been computed:
The COM results have been compared with the ones obtained by:
The 2D antiferromagnetic Heisenberg model has been investigated by considering a two-pole approximation in the bosonic sector. The development of a short range antiferromagnetic order has been described by a nearest neighbor spin-pair order parameter. The calculation of the static susceptibility as a function of the temperature shows a crossover from the Curie-Weiss behavior to the spin liquid one. The agreement with numerical and analytical approaches is reasonably good.