Coherent states and nonlinear dynamics of the three state quasi-spin modelwith soliton solutions

In this paper the generalized coherent states defined as points of the cose t space SU(2)/U(1) are used as trial wave functions in order to study the q uasi-spin model of the nonlinear phi(6)-theory. In the simple version of th e quasi-classical theory deduced from this method a complete integrable sys tem is obtained. In a general context, the ground state and linear spectrum of the nonlinear lattice equation were evaluated. Finally, by analyzing th e effective potential, the first and second order phase transitions are sho wn to exist. Copyright (C) 1998 Elsevier Science B.V.