Accurate MR CI studies of the N 2 ground state

Abstract

Extensive calculations of the ground-state energy of the N 2 molecule have been performed by means of the MC SCF and MR CI(SD) methods which are defined in terms of a 20-configuration reference space including all the configurations required for a correct description of the dissociation of the triple bond. The AO basis contained the 3d2flg polarization set. The whole potential curves have been obtained using the same approach. The calculations yields the lowest total energies and the most accurate results for D e ( = 9.629 eV) and R e ( = 2.078 au) obtained so far in extensive variational calculations. Further evaluation of the quality of our potential curves is made by comparing vibrational intervals, rotational constants and several spectroscopic constants with experimental values. A very satisfactory agreement has been found.