Abstract
The perturbation to the cubic crystalline field at rare-earth ions substituting the cation in CaF2 is treated as a point-charge Coulomb field of the compensating ion. The cubic field energy states and the local charge compensation have enabled the author to calculate the wavefunction and g-values of Yb3+ and Ce3+ with tetragonal symmetry in CaF2. The results for Yb3+ turn out to be in reasonable agreement with experimental g-values, while those for Ce3+ seem not unsatisfactory.