An approximation to the non-relativistic Coulomb propagator, correct to second order in h, is derived. The result is expressed in terms of the auxiliary variables introduced in the solution of the corresponding Hamilton-Jacobi equation. Higher-order contributions can be computed as required, but no explicit summation of the expansion has yet been found.
Peer Reviewed
http://deepblue.lib.umich.edu/bitstream/2027.42/26797/1/0000353.pdf