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 (α∥=2.15 Å3, α⊥=0.77 Å3), the magnetic susceptibility (extrapolated to —10.2 ppm), the magnetic shielding [σ=—276 at F or —200 at C (preferred value); σexpt1=—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); Cexpt1=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.