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 19 F 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 5 s 4 p contracted Huzinaga/Dunning basis. In series II, the 5 s 3 p basis set was uncontracted in several steps until 9 s 5 p 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 .