Density functional study of magnetic coupling parameters. F and H hyperfine splitting in the prototype inorganic (d1) and organic (p1) radicals TiF3 and CH3

Hyperfine splittings (hfs) are calculated for the title compounds. These calculations resolve the discrepancy found earlier between the calculated and experimental hfs for F in TiF3 by (a) careful consideration of the spin polarization effects in the occupied 2s and 2p shells, as well as the nonnegligible spin polarization of the 1s shell, and (b) reconsideration of the experimental results by redefining the relative signs of the principal values of the A tensor on the basis of the calculations. The presently available density functionals (LDA, GGA’s) are shown to yield fair agreement for the magnetic coupling parameters, indicating the usefulness of the DFT calculations for interpretation of ESR data of large complexes. Such interpretation is difficult on the basis of the experimental hfs data only, due to the intricacies of the spin polarization mechanism that gives rise to them.