The Influence of Two-phonon Correlation on the Ground-state Energy of Bound Magnetopolaron

Based on LLP canonical transformation,a different polaron ground-state which includes the two-phonon correlation is adopted to calculate the ground-state energy of coulomb bound magnetopolaron.The calculation indicates that the energy created by two-phonon correlation is relative to coupling constant.The result shows that ground-state energy is lowered taking two-phonon correlation into account.