Spectral density for the tunneling current zero-frequency shot-noise in a one-dimentional mesoscopic system

We have derived the expression of the spectral density for the current shot -noise in terms of the nonequilibrium Green's functions( closed-path Green' s functions) for a. one-dimensional mesoscopic junction, and performed nume rical calculations to discuss the dependence of the zero frequency spectral density for the currentshot-noise on other variables when the tunnling jun ction is pure or impure.