Pair correlation function, interaction-induced

In studying the intense laser interactions with the CS2 molecules, and observing the behaviour of the orientational distribution and pair correlation functions [g(S)J through the time-evolution of the optical field-induced anisotropy, we are emphasizing external field-induced phenomena rather than interaction-induced or collision-induced events. 

We can turn now to answer a frequently asked question, Why do we say that the F-F is bonded by charge-shift resonance, isn t it bonded simply by electron correlation The MO-based conclusion that F-F is bonded by electron correlation is rooted at the fact that at the HF level the molecule is not bonded and electron correlation, which is brought about by configuration interaction (Cl), is required to induce bonding. Let us recall that the HF wave function ( Phf) for an electron-pair bond A-A is described by 50% covalent and 50% ionic characters, which means that there are identical probabilities for the two electrons to reside on the same atom or being separated apart, one on each atom. Thus, the two electrons in Phf are not correlated, and electron correlation is obtained by complementing... 

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