Theoretical study of atoms by the electronic kinetic energy density and   stress tensor density
  We analyze the electronic structure of atoms in the first, second and third periods using the electronic kinetic energy density and stress tensor density, which are local quantities motivated by quantum field theoretic consideration, specifically the rigged quantum electrodynamics. We compute the zero surfaces of the electronic kinetic energy density, which we call the electronic interfaces, of the atoms. We find that their sizes exhibit clear periodicity and are comparable to the conventional atomic and ionic radii. We also compute the electronic stress tensor density and its divergence, tension density, of the atoms, and discuss how their electronic structures are characterized by them. 
Hiroo Nozaki, Kazuhide Ichikawa, Akitomo Tachibana
physics.atom-ph cond-mat.mtrl-sci physics.chem-ph