On the utility of momentum space in the density functional theory description of the steric effect

This paper assesses the utility of momentum space in the density-based quantification of the steric effect proposed by Liu [J. Chem. Phys. 126, 244103 (2007)], which is based on a new energy partition scheme where the total electronic energy is decomposed into contributions from three independent effects: steric, electrostatic, and the fermionic quantum. The steric energy defined in this way is repulsive, exclusive, and extensive and intrinsically linked to Bader's quantum theory of atoms in molecules. In this work, the plausibility of defining and computing steric energies using momentum densities according to this scheme is confirmed from numerical tests. Moreover, we found that the correlation between the experimental scales of the steric energies and theoretical values computed from momentum densities is even better than the same correlation with theoretical estimations obtained from position densities.