Nuclear derivative coupling elements in CSF representation

We here concentrate on the CSF representation in somewhat greater detail. The first order nuclear derivative CSF coupling elements are expressed in terms of the following equation 

Since molecular orbitals 4 i are usually prepared as a linear combina- 

1 The first order derivative of the molecular orbital coefficients 

Since the case for the AOs is rather straightforward, here we are concerned only with the first order derivative over molecular orbital coefficients with respect to the nuclear coordinates. There are four points to be considered (i) Implicitly the term c)j depends only on (ii) We should formu- 

Chemical Theory Beyond the Born-Oppenheimer Paradigm 

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