Perturbed hartree-fock calculations. IV. Second-order properties of the fluorine molecule

The coupled Hartree-Fock method with a limited basis set has yielded values at the F nucleus and at the center of charge C of the F2 molecule for the electric polarizability (αII=2.15 Å3, α1 = 0.77 Å3), the magnetic susceptibility (extrapolated to -10.2 ppm), the magnetic shielding [σ= -276 at F or -200 at C (preferred value) ; σexptl= -210 ppm], rotational magnetic moment (extrapolated to -0.108 nuclear magnetons) and spin rotation constant [CF=169 at F or 152 at C (preferred value); Cexptl= 157±2 kc/sec]. The poor gauge dependence for the shielding and spin rotation constant is associated with the unusually high paramagnetic shielding at F which is due specifically to an interaction of the occupied πu orbital with a low-lying excited σu state. The susceptibility and rotational magnetic moment did not vary extensively with change of gauge.