Correlation between reactivity descriptors and electronic pressures: A different application of SBO orbitals

This research has discovered relationships between atom reactivity parameters (such as electronegativity or hardness) and the pressure exerted on their electronic shells. These relationships are derived from the relationship between the radius of the atom confined within a spherical box and the pressure exerted on the box by its electrons. To determine the pressure corresponding to each radius, it was essential to formulate a set of new basis functions valid for calculating the energy of confined atoms. These new basis functions, Simplified Box Orbitals (SBOs), stem from the previously studied SBOs, but their coefficients are obtained variationally instead of being fitted to a Slater-Type Orbital (STO), and the powers (R−r)^k are selected differently. These differences make them especially suitable for treating confined atoms and distinguishing between “hard” and “soft” confinements. This methodology has proven useful for accurately calculating the properties of various atoms under different pressures, namely H, He, Li, Be, B, C, N, O, F, and Ne. Furthermore, we believe that the new basis functions are suitable for obtaining Gaussian expansions that will enable the treatment of confined molecules, which we intend to study in a subsequent work.