Fig. 2. The two-sided coordination environment and bond length distribution in the fivefold axes.

a Twelve axes of ICNP-1, consisting of six C5 and six C5′ axes, with ending atoms marked as red and green, respectively. b Front and top views, and atomic slices through the raw reconstruction of the central icosahedron, enlarged from the black box in (a). Scale bar: 1 nm. c, d Two types of atom columns composed of one C5 axis and one C5′ axis. The edge dislocations change the coordination of axial atoms either to become 13-coordinated pseudo-D_h atoms (c), or to slip into the adjacent parallel column to form a new axis (d). e–g Front and top views, and atomic slices through the raw reconstruction of the repeating coordination units, enlarged from the blue, green and purple box in (c, d), respectively. The gray shadows highlight the coordination planes above and below the center atom. Scale bar: 1 nm. h An ideal decahedron consisting of three types of atomic bonds. The α, β, and γ represent the capping, capping-ring, and ring atom bonds, respectively. i The deviations of averaged bond lengths of α (yellow), β (dark green), and γ (light green) from the outer surface of C5′ axes to the outer surface of C5 axes, by subtracting the standard Au–Au bond length (2.88 Å). The distance between two neighboring D_h atoms, α, is more and more compressed from C5 axes to C5′ axes. β remains compressed in C5 axes but becomes stretched in C5′ axes. The γ bonds are stretched in both C5 and C5′ axes. The error of averaged bond length of α, β, and γ bonds are estimated using the standard deviation of the bond length (Supplementary Note 2). The confidence interval in (i) is 95%. The balls in the atomic model with yellow, blue, light purple, and dark purple color represent the atoms with fcc, hcp, D_h, and I_h structure, respectively. The balls in the atomic model with red and green color represent the ending atoms in fivefold and sixfold axis, respectively. Source data are provided as a Source Data file.