Charge transfer and hybridization in ionic bonding

Charge- leakage breakdown of the classical ionic picture lithium fluoride 

Let us examine the quantal energy curve in more detail. On chemical grounds we expect that LiF formation should be reasonably well described by a 

The irregular shape of the CT curve near Req reflects competition of unfavorable donor-donor interactions (steric repulsions) and favorable donor-acceptor 

Still another aspect of the Li and F valence orbitals is modified by ionic-bond formation. In an isolated ionic or neutral species, each NAO retains the characteristic angular shape of the pure s and p hydrogenic orbitals shown in Fig. 1.1, reflecting the full rotational symmetry of atoms. However, in the presence of another atom or ion this symmetry is broken, and the optimal valence orbitals acquire sp hybrid form (assumed for simplicity to include only valence s and p orbitals), as represented mathematically by 

In this expression, the hybridization parameter A, varies between 0 (pure s) and oo (pure p), with any integer or non-integer value in this range being physically allowed. The general relationships between k and percentage s and p characters are given by 

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