Vibrational matrix elements of the quadrupole moment of N2(x1Σg+)

The quadrupole moment ( Theta zz) of the ground state of molecular nitrogen has been calculated with accurate Hartree-Fock and generalized valence bond wavefunctions. The dependence of Theta zz on internuclear separation differs markedly in the two approximations, reflecting the inability of the Hartree-Fock wavefunction to correctly describe dissociation. This difference has a substantial effect on the calculated vibrational matrix elements of the molecular quadrupole moment, especially for large off-diagonality.