Dipole moment of IF and other interhalogen molecules

The dipole moment of IF and the remaining five interhalogen halides are computed at the MBPT(4) level employing effective potentials. A comparison between the finite-field and the Hellman–Feynman expectation value approach is presented. The theoretical values are in agreement with the experimental ones to within 10%. In the case of IF, whose dipole moment is unknown, we predict a value of 1.87±0.2 D. The correlation corrections constitute about 20% to 30% of the total dipole moment value, the dominant part of which is introduced at the second order. Only slight differences occur between the Hellman–Feynman expectation value formula and the finite-field procedure for dipole moments at the level of a second-order MBPT wave function.