Non-nuclear maxima of the electron density on alkaline metals

The topological properties of the electron density of bcc alkaline metals (Li–Cs) is examined by means of Hartree–Fock and density functional calculations. Our best results indicate that lithium is the only alkaline metal showing non-nuclear maxima (NNM) at the room pressure and temperature experimental geometry. Sodium and potassium, but not rubidium and cesium, would also present NNM under an appropriate compression, even though the NNM in potassium would be residual at best and contain a negligible amount of electrons. Despite these differences, all five alkaline metals share a common tendency towards topological change that makes their behavior clearly distinct from what is typical in ionic, covalent and molecular crystals. When examined in a wide range of interatomic distances, the electron density of every metal follows a well defined topological sequence, with strong similarities across the five metals.