The electrostatic energy is a
quasi-classical quantity introduced by the distribution of electronic
clouds and nuclei, considering unperturbed fragments put
in contact, without allowing their deformation. The orbital effects
have a complex nature, related with the final orbital mixing and
relaxation of the fragments into their final form in the molecule.
Therefore, this contribution can be considered a measure of the
covalent effects, although includes many others, such as charge
transfer, Coulomb components aside the kinetic and exchange
ones.