Fig. 2. Core, subsurface and surface shells of the lowest-energy Pd₇₀X₇₀ (X = Au, Ag, Cu, Zn) homotops according to density functional calculations. Spatial dimensions of the NPs are also indicated (for Pd₇₀Zn₇₀ the dimensions are given in two directions). Pd atoms are displayed as cyan spheres; atoms X – as spheres of other colors.