A stationary phase analysis of the reduced propagator gives the semiclassical reduced propagator and the Pechukas equation. Taking the semiclassical limit, we derive a mixed quantum-semiclassical time correlation function using Pechukas' stationary phase analysis. This derivation incorporates the initial configuration variations of Xiao and Coker and the initial value formalism of Heller and Miller. To simplify the correlation function further, we employ a zero back reaction approximation, while noting the nonuniqueness property of the solution to the Pechukas equation subject to initial conditions. The limitations of this approximation were discussed. (C) 1997 American Institute of Physics.