The "mixed" Green's function approach to quantum kinetics with initial correlations

A method for deriving quantum kinetic equations with initial correlations is developed on the: basis of the nonequilibrium Green's function formalism. The method is applicable to a wide range of correlated initial states described by nonequilibrium statistical thermodynamics. Initial correlations and the real-time evolution are treated by a unified technique employing many-component "mixed" Green's functions. The Dyson equation for the mixed Green's function leads to a set of equations fur real-time Green's functions and nsw (cross) components linking initial correlations with dynamical processes. These equations are used to formulate a generalized Kadanotf-Baym ansatz for correlated initial states. A non-Markovian short-time kinetic equation is derived within the T-matrix approximation fur the self-energies. The properties of the memory kernels in this equation are considered in detail in Born approximation for the T-matrices. The kinetic equation is demonstrated to conserve the total energy of the system. An explicit expression for the time-dependent correlation energy is obtained. (C) 1999 academic Press.