The isotropic magnetic susceptibility, chi(iso), for F-2 has been measured
experimentally for the first time and found to be (-9.627 +/- 0.062) x 10(-
6)(cgs). The value was measured on a paramagnetic gas analyzer (PGA) config
ured to be compatible with the aggressive F-2. The PGA was Shown to respond
linearly with chi(iso) and was calibrated using the response from several
pure gases and their literature chi(iso) values. The major source of error
in the analysis is the inaccuracy of the literature chi(iso) values. The ex
perimental result for F-2 was compared to ab initio calculations using both
Hartree-Fock (HF) theory and gradient-corrected density functional theory
(DFT) theory with a variety of basis sets. DFT calculations were found to c
onverge to a value much closer to the experimental value compared to HF cal
culations, underlining the importance of the many-electron correlation effe
ct in F-2.