The transport properties and second virial coefficient of helium have been calculated for two hybrid intermolecular potentials recently proposed by Bruch and McGee, and the results are compared with experi-mental values. Tables of transport collision integrals for the helium isotopes which are accurate to several parts per thousand were prepared for the temperature range 0.8-2500°K in order to adequately span the existing data. The collision integrals were computed by an exact quantum phase-shift calculation at low temperatures followed by a JWKB approximation and classical calculation at intermediate and high tem-peratures, respectively. The bulk properties were then evaluated using the prepared tables. The agreement with experimental measurements for the various properties at low temperatures is rather poor when com-pared with the results calculated using the Lennard-Jones (12-6) potential. We conclude that this is due to excessive depth of the potential well. On the other hand, the calculations above approximately 150°K agree quite well with experimental data which leads us to the conclusion that the low-energy repulsive region of either hybrid potential is a good representation of the helium-helium interaction. Since the potentials are essentially identical in this region and independent of the long-range attractive terms, it is suggested that for practical applications the Morse-FOD potential be truncated to the much simpler Morse potential with the given parameters and its region of validity restricted to temperatures above 150°K.
