Natural atomic orbital based energy density analysis: Implementation and applications

We present an improvement of energy density analysis (EDA), which partitions the total energy obtained by Hartree-Fock and/or density functional theory calculations, with the use of the natural atomic orbital (NAO) [A.E. Reed et al., J. Chem. Phys. 83 (1985) 735] and Löwdin's symmetric-orthogonal orbital (LSO). The present NAO- and LSO-EDA schemes are applied to analyses of CO2 and Li9+ with various basis sets. Numerical results confirm that NAO-EDA exhibits less basis-set dependence, while the conventional results are very sensitive to the adopted basis sets.