STOCHASTIC SOLUTION TO HIGHLY NONLOCAL ACTIONS - THE POLARON PROBLEM

A stochastic technique for highly nonlocal actions has been developed and applied to the Frohlich Hamiltonian describing an optical polaron. The energy and the effective mass of the polaron are obtained for a wide range of couplings. Monte-Carlo results with high statistics are presented which allow a test of the various approximation methods used for the polaron problem. The high accuracy is accomplished by combining Feynman's variational approach with partial averaging over the higher Fourier components in the path-integral formulation. The present method is compared to other path-integral Monte-Carlo approaches.