On the separation of the information content of the Fermi and Coulomb holes and their influence on the electronic properties of molecular systems.

In this paper, two information-based functions are employed as a real space measure of the Fermi and Coulomb holes for same-spin electrons. The first one is the information content of the Exchange-Correlation hole, calculated from the Kullback-Leibler divergence of the same-spin conditional pair density respect to the marginal probability (). As reported previously, , can be used to reveal the regions of the space associated to the classical electron pair model. Here, correlated wave-functions, such as CISD, MP2, and CCSD, are considered for the calculation of . This is achieved by introducing an approximated method based on employing natural orbitals and their occupancy numbers. In addition to , in this work we propose a measure of the information content of the same-spin correlation hole, which is computed in terms of the Kullback-Leibler divergence of a correlated same-spin conditional pair density respect to the uncorrelated Hartree-Fock pair density (). The proposed methodology is discussed in the light of the result derived from noble gas atoms, the molecule and some non-covalently bonded systems. [ABSTRACT FROM AUTHOR]