Polaron-soliton squeezed states , ground state and quantum fluctuation in one-dimensional molecular crystals

Abstract

On the basis of the Hamiltonian of the Holstein one_dimensional molecular crystals, using the squeezed_coherent state expansion method, the influence of the electron_two phonon interaction on the properties of the ground state and quantum fluctuation for the polaron_soliton system were investigated by including the quantum correlation between the polarons and the squeezed phonons, and the renormalized displacement correction.The nonlinear Schringer equation for one_dimensional polaron_soliton state has been found in a closed form.By the use of the nonlinear expansion, we have given the analytical solution of the corresponding nonlinear equation so as to obtain the ground state energy,the quantum fluctuation and the polaron energy of the polaron_soliton system in analytical form. We have found that, when the electron_two phonon coupling strength g1g12n〉 and 〈Δ2p〉〈Δ2q〉 for the two-phonon effect are larger than the one_phonon one and the polaron energy for the two_phonons effect is more negative compared with the one_phonon one.