Consistent path-integral study for a single electron in a thermal crystal with an applied electric field

A single electron drifting in a thermal crystal is studied under an applied electric field with the applied field and the electron-phonon interaction being treated nonperturbatively. With the help of the path-integral approach of the nonequilibrium Green's function, a set of coupled equations is derived to describe consistently the drift motion and fluctuation where the balance of momentum is consistent with the balance of energy. By solving these equations, various aspects of the nonlinear nonequilibrium electron transport properties are obtained. (Author)