The hyperfine coupling constants of 19F: An ab initio MRD-CI basis set study

The isotropic (a_iso) and dipolar (A_dip) hyperfine coupling constants of ¹⁹F were obtained from MRD -CI wave functions using a variety of basis sets. In series I, increasing numbers of d functions were added to a 5s4p contracted Huzinaga/Dunning basis. In series II, the 5s3p basis set was uncontracted in several steps until 9s5p was reached, to which were added from one to three d-polarization functions. CI parameters (selection thresholds and the number of reference configurations) were also varied. A study of the R dependence of a_iso and A_dip was performed. The best values obtained at R_e are 260 G for a_iso and 308 G for A_dip, compared with experimental values of about 280 G for a_iso and 320 G for A_dip.