Generalized coherent states and nonlinear dynamics of a lattice quasispin model

The nonlinear lattice equation of the phi(6) theory is studied by using the technique of generalized coherent states associated to a SU(2) Lie group. We analyze the discrete nonlinear equation with weak interaction between si tes. The existence of saddles and centers is shown. The qualitative paramet ric domains which contain kinks, bubbles and plane waves were obtained. The specific implications of saddles and centers to the parametric first- and second-order phase transitions are identified and analyzed. (C) 2000 Elsevi er Science Ltd. All rights reserved.