Fig. 4.

DFT results. a The truncated octahedron of 79 atoms. This structure has 19 internal sites, i.e. 18 subsurface sites plus the central site. b–g Structures of Ag₆₇Pt₁₂. Each cluster is shown in two views. Pt atoms are in red and Ag atoms in grey. Pt and Ag atoms are shown as large and small spheres, respectively, with the exception of the left view of (e), in which all atoms are shown as large spheres. In (b), the perfect L1₁@Ag-skin phase is shown. The numbers give the DFT energy differences from the lowest-energy homotops, which are the perfect L1₁@Ag-skin structure shown in (b) and the structure in (c). DFT density functional theory