The Einstein-Hamilton-Jacobi equation: Searching the classical solution   for barotropic FRW
  The dynamical evolution of the scale factor of FRW cosmological model is presented, when the equation of state of the material content assume the form $\rm p=\gamma \rho$, $\rm \gamma=constant$, including the cosmological term. We use the WKB approximation and the relation with the Einstein-Hamilton-Jacobi equation to obtain the exact solutions. 
S. R. Berbena, A. V. Berrocal, J. Socorro and Luis O. Pimentel