IONIZATION RADII OF COMPRESSED ATOMS

The compression of all atoms has been modelled by changing the free-at om boundary condition obeyed by electronic wavefunctions, from r lim/- -> infinity, PSI(r) = 0 to r lim/--> r(o), PSI(r) = 0, r(o) < infinity , in numerical Hartree-Fock-Slater calculations of electronic energy l evels. As r(o) decreases, energy levels increase uniformly and by tran sferring 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, comm ensurate with the known chemistry of the elements, and introduce a new fundamental theoretical parameter that could serve to quantify chemic al reactivity. Insofar as the compression of atomic wavefunctions occu rs within crowded environments that lead to chemical interactions, ion ization radii provide a more realistic index of the chemical propertie s of atoms in the bulk, than ionization energies, which are more appro priate in spectroscopic analyses of free atoms.