HFS Constants of OH Ground State

Fermi contact term at the proton in the OH ground state is pointed out to be negative either from a simple qualitative consideration or from an LCAO MO CI calculation. The calculated value agrees well with the experimental value revised recently by Radford. Other hfs constants, 〈1/r3〉H and 〈2P2(cosχ)/r3〉H, are also calculated by a single configuration approximation with the use of an analytical Hartree—Fock orbital. The results agree quite well with the experiment, although the agreement is somewhat worse for 〈sin2χ/r3〉H.