STATIC DIPOLE POLARIZABILITY OF THE FLUORIDE-ION

The reliability of the recent empirical value of the electric dipole polarizability of the free fluoride ion due to Coker (1.48 · 0.08 Å3) is discussed by a comparison with the corresponding accurate theoretical data for the He isoelectronic series. It is concluded that the true free fluoride ion polarizability should be much higher than both the empirical value and the accurate CHF result of Cohen (1.56 Å3). The calculations of the second-order correlation correction of the CHF polarizability of the F- ion by using three different GTO basis sets with explicit dependence on the external electric field strength (so-called EFV GTO bases) show that the correlation contribution is quite large and positive. These calculations lead to the free fluoride ion polarizability as large as about 2.4 Å3. The discrepancy between the theoretical and empirical estimates is interpreted in terms of the medium effects. Similar discrepancies for the heavier halide ions are also expected. It is also pointed out that the proportionality between the polarizability values and the inverse fourth power of the screened nuclear charge does not in fact provide any reliable criterion for the accuracy of the polarizability data for negative ions. © 1979 American Chemical Society.