New Fourier path integral method, a more general scheme for extrapolation, and comparison of eight path integral methods for the quantum mechanical calculation of free energies

Five different discretized path integral (DPI) methods were transformed into Fourier path integral (FPI) schemes using an isomorphism of Coalson. A highly effective perturbation correction scheme was applied to the DPI methods, to correct the error in the numerical evaluation of the propagator. The efficiency of the rescaled fluctuation FPI method and that of the Fourier analog methods, compare well with the original FPI method.