A Laplace transform relation between the distribution function $\exp \{-\beta H\}$ in quantum statistical mechanics and the Green's function of the wave equation has been noted by Koppe. This relationship may be extended to the stationary-state scattering equation. General properties of the transformation are discussed. Applications to the evaluation of the virial coefficients are considered. A further application of the perturbation methods of Brueckner and his collaborators is described.

• Received 8 March 1956

DOI:https://doi.org/10.1103/PhysRev.103.489