Commensurate-incommensurate crossover in quantum sine-Gordon model

Abstract
The thermodynamics of the quantum sine-Gordon model with finite winding numbers is investigated by the Bethe ansatz method. The temperature dependences of the specific heat and the winding number are calculated. The crossover from the case with the commensurate ground state to that with the incommensurate ground state is discussed. The quantum effect is shown to be significant in the thermodynamic properties of the system.