HYPERFINE AND NUCLEAR-QUADRUPOLE COUPLING IN CHLORINE AND FLUORINE DIOXIDES

The hyperfine and nuclear quadrupole coupling tensors have been calcul ated for the two chlorine dioxide isomers OC10 and C100 and for fluori ne dioxide FOO. The coupled-cluster singles and doubles (CCSD) approac h with a perturbative treatment of triple excitations [CCSD(T)] has be en used and basis saturation has been investigated. For the symmetric isomer OC10 close agreement is obtained with the accurate and detailed experimental data. For FOO a geometry optimization as well as a compa rison of calculated and experimental hyperfine coupling tensors sugges t a shorter F-O bond length than that obtained experimentally. For the isomer C100, calculations have been carried out at the theoretical eq uilibrium geometry determined by Peterson and Werner and at the geomet ry proposed by Byberg for the matrix isolated molecule. The hyperfine coupling tensors obtained at these two geometries are substantially di fferent, but the estimated accuracy of the calculations is not high en ough to allow a determination of the geometry of C100 from the hyperfi ne data. (C) 1997 American Institute of Physics.