Exact Results in Quantum Theory

The interaction energy between two ground-state atoms behaves as 1/R^6.for distances smaller then that of the lowest transition wavelength, and so does the finite nuclear mass correction to the energy. For larger distances the interaction energy is modified by the retardation of the electromagnetic interactions and asymptotically falls-off as 1/R^7. We have derived the finite nuclear mass correction to the retardation of the atom-atom potential, and have shown that besides the expected contribution from the finite masscorrection to atomic matrix elements another term is present.