Ionization radii of compressed atoms

Abstract

The compression of all atoms has been modelled by changing the free-atom boundary condition obeyed by electronic wavefunctions, from r [graphic omitted] ∞, ψ(r)= 0 to r [graphic omitted] r_o, ψ(r)= 0, r_o < ∞, in numerical Hartree–Fock–Slater calculations of electronic energy levels. As r_o decreases, energy levels increase uniformly and by transferring the excess energy, an electron escapes from the valence shell when compression reaches a critical value of r_o, characteristic of each atom. These ionization radii display remarkable periodicity, commensurate with the known chemistry of the elements, and introduce a new fundamental theoretical parameter that could serve to quantify chemical reactivity. Insofar as the compression of atomic wavefunctions occurs within crowded environments that lead to chemical interactions, ionization radii provide a more realistic index of the chemical properties of atoms in the bulk, than ionization energies, which are more appropriate in spectroscopic analyses of free atoms.