Steric effects from the perspective of Pauli energy

Pauli energy, representing the portion of the kinetic energy that embodies all the effects from the antisymmetric requirement of the total wave function by the Pauli exclusion principle, is proposed as a density-based measure for one of the most widely used concepts in chemistry and physics, namely steric effects. Our main idea originates from the fact that in areas where there are steric effects, the repulsions originated from the Pauli exclusion principle are also present. Since the majority of these repulsions are quantified by the Pauli energy, steric effects can be measured by the Pauli energy as well. To validate the proposed idea, it is shown numerically that the Pauli energy expressions based on approximate kinetic energy density functionals (KEDs) can reproduce the experimental steric scales of different compounds. Indeed, although some KEDs do not predict the accurate results of kinetic energy, their description for steric effects from the perspective of Pauli energy may be desirable. On the other hand, there are also some KEDs that provide much better results than others, while their shortcomings can still be unveiled when they are used to quantitative description of steric effects using Pauli energy.