THE N-2-N-2 POTENTIAL-ENERGY SURFACE

Extensive ab initio calculations of the N-2-N-2 interaction energy hav e been performed to define its anisotropic behavior with respect to mo lecular orientation. Additional calibration calculations with larger b asis sets have been used to improve the theoretical energies at small separation distances and have been combined with experimental data for the second virial coefficient (including the results of the more rece nt second acoustic measurements) to determine a realistic rigid-rotor potential energy surface for the van der Waals region. (C) 1997 Elsevi er Science B.V.