The kinetic energy change on covalent bond formation

Abstract

Stimulated by an analysis of the classical molecular orbital and valence bond descriptions of the two-electron normal covalent bond (both faulty), the argument is made that there exist good representations of the kinetic energy change ΔT, on nonpolar covalent bond formation in a diatomic molecule, of the form ΔT(R) = ∫F(R - r′)S(r′)dr′. Here F is a nonlinear response function which itself involves the overlap S. The kinetic change is known to satisfy the sum rule ∫₀ ^∞ΔT(R)dR = Z_αZ_β exactly; it is shown how this can be built into the treatment by the use of Fourier transform methods. Also considered is ∫₀ ^∞ΔT(R)R ² dR, which is an important additional property of the kinetic energy change. Representation of ΔT(R) as a Morse function, already known to be highly accurate, is shown to exactly conform to the proposed form.

• chemical bond
• momentum space
• Morse curves