Fig. 6
From: Oxidative reactivity of alkali-like superatoms of group 5 metal-encapsulating Si16 cage nanoclusters
Isosurfaces for the difference electron density between M@Si16+ and M@Si162+. Those for a M = V, b Nb, and c Ta are calculated with the def-TZVP basis set, where the blue (red) region corresponds to the decrease (increase) of electron density difference (Δρ) at Δρ < –0.0008 e–/a.u.3 (Δρ > + 0.0008 e–/a.u.3). In the calculations, the geometric structure is fixed to that optimized one for M@Si16+. The decrease of Δρ outside the Si cage is significant in Nb@Si16, as shown by circles with dotted lines
