A BORN-OPPENHEIMER APPROXIMATION FOR PATH-INTEGRALS WITH AN APPLICATION TO ELECTRON SOLVATION IN POLARIZABLE FLUIDS

The Born-Oppenheimer approximation is introduced into the path integral expression for the canonical partition function. It is difficult to apply this to simulations. We devise a new adiabatic expression which we call the free energy Born-Oppenheimer approximation which is much easier to simulate. It is shown that this approximation deviates from the exact path-integral expression by no more than does the standard Born-Oppenheimer approximation and we apply it to the problem of an excess electron dissolved in a polarizable fluid.