Average potential energy criterion: Force fields of some planar XY3 and tetrahedral XY4 molecules

Minimization of the average potential energy contributions from bending deformations due to zero point vibration serves as a good criterion for fixing the harmonic force fields in planar XY₃ and tetrahedral XY₄ nonhydride molecules. An explanation based on the concept of rehybridization of the orbitals of the central atom during a bending vibration is offered.