The hetero-polar diatomic molecule non-self-consistent treatment

The hetero-polar diatomic molecule (non-self-consistent treatment) 

The sign is associated with the filled bonding state (B) and the -I- sign to the empty anti-bonding states (AB). The energy difference between the 

The link with Phillips spectroscopic model becomes apparent ec — eA. is the hetero-polar (ionic) contribution to the gap, while 2)5 is the covalent contribution. 

In the bonding state, the anion and cation electron numbers Na and Nc, respectively, are equal to  

If one assumes for example that both neutral A and C atoms bear one outer electron, 1 — Na and 1 — Nc determine the ionic charges. The charge is negative on the anion and positive on the cation. Its absolute value is equal to  

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