Soliton lattice and phase transition in generalized Sine-Gordon model

The generalized Sine-Gordon (Pokrovsky-Talapov) model is examined. Two different solutions for the model is discussed and corresponding energy density is calculated. It is shown, that for the different value of the modification parameter, the ground state is described by different solutions. Corresponding critical value of modification parameter, at which the phase transition from one solution to other occurs, is obtained.