ON CALCULATING PHASE SHIFTS AND PERFORMING FrrS TO SCATl-ERlNG CROSS SECTIONS OR TRANSPORT PROPERTIES*

Improved methods of cakulatin ~ quantum mechanical phase shifts and for performizxg Ieast-squares tits to scattering cross sections or transport properties, are described. Their use In a fiw-Ixrameter fit to experimental differential cross sections reduces the computer time by a factor of 4-7. Differential and integral scattering cross sections measured by molecular beam scattering techniques are an important source of information about intermolecular potential energy functions [l-3] _ In general, potent&k may be obtained from data of this type either by use of formal inversion procedures, or by using least squares fits to determine the values of the potential parameters which yield the best agreement between calculated an