Effective Hamiltonian, Mori Product and Quantum Dynamics
  An appropriate extension of the effective potential theory is presented that permits the approximate calculation of the dynamical correlation functions for quantum systems. These are obtained by evaluating the generating functionals of the Mori products of quantities related to the relaxation functions in the (PQSCHA) pure self consistent harmonic approximation. 
A.Cuccoli, V.Tognetti, R.Giachetti and R.Vaia