G. Barton, Long-range Casimir-Polder-Feinberg-Sucher intermolecular potential at nonzero temperature - art. no. 032102, PHYS REV A, 6403(3), 2001, pp. 2102
A simple Hamiltonian determines in closed form the potential of the long-ra
nge force between two fixed molecules polarizable magnetically as well as e
lectrically, exposed to blackbody radiation at temperature T. The results a
pply provided kT<<(h) over bar Omega and at separations rho>>c/Omega, with
(h) over bar Omega a typical molecular excitation energy.