A variational-perturbation approach is invoked to study the effect of the
environment potential around Fluoride ion on some important electronic properties.
The dipole polarisability α, oscillator strength S(-٢) and S (-١) and magnetic
susceptibility χ are theoretically estimated for Fluoride ion in different potentials.
Also we calculate these electronic properties in many Fluoride structure crystals
such as CdF٢, CaF٢, PbF٢, SrF٢ BaF٢, and LiF.