RELATIVISTIC AND CORRELATION-EFFECTS ON MOLECULAR-PROPERTIES - THE INTERHALOGENS CLF, BRF, BRCL, IF, ICL, AND IBR

The effect of relativity on the properties of the interhalogens ClF, B rF, BrCl, IF, IBr, and IBr is studied by comparing relativistic and no nrelativistic calculations. Bond lengths, harmonic frequencies, and di ssociation energies show that the bond is weakened in the relativistic formalism. Relativity increases the electric dipole moment whereas th e electric quadrupole moment and dipole polarizability display an irre gular behavior. The relativistic contributions to the electric dipole and quadrupole moment of the iodine containing molecules are 10%-20% o f the total value, whereas the contributions in the other molecules ca nnot be neglected. The value of the electric quadrupole moment is domi nated by the relativistic contributions. (C) 1998 American Institute o f Physics.