WHICH DOUBLE-OCTET ABC MOLECULES ARE BENT - CI CALCULATIONS ON CAF2, AND A SOFTNESS CRITERION TO PREDICT BENDING

Hartree-Fock and configuration interaction calculations for CaF2 yield a bond angle of 155° only after d-type polarization functions are included, suggesting that "anomalous" bent geometries can be rationalized by polarizability. A criterion using the chemical softness as a measure for both polarizability and low-lying valence states, completely separates the bent from the linear double-octet ABC molecules. Sixty yet unreported bent structures are predicted, and new experiments suggested. © 1990.