An Effective Description of Electron Correlation in the Green Function Approach

Beyond the usual many body perturbation theory,with the eigenfunctional theory,we directly calculate the correlation function produced by the Coulomb interaction of electrons in the equation of one-electron Green function,and give the general expression of the non-local effective interaction potential in a Hartree-type potential,which is absent in all previous many body perturbation theories.This effective interaction potential originates from the quantum many body effect of the system,and it cannot be obtained directly by the usual perturbation expression approach.Moreover,using theoretical models,we demonstrate that this effective interaction potential can be used to characterize the electron correlation strength of the system.