Simple Cubic (SC)
The simplest crystal structure, with atoms placed only at the corners of a cube. It's relatively rare in nature due to its low packing efficiency. Polonium is a known example.
The First Brillouin Zone
The shape you see is the Brillouin Zone, which is the fundamental 'unit cell' of reciprocal space. It's a map used by physicists to plot a material's electronic band structure and phonon dispersion. Its complex shape (like this truncated octahedron for FCC) is a direct consequence of the crystal's symmetry.
High-Symmetry Path
The labeled points (Γ, X, L, etc.) are special locations of high symmetry. The yellow line traces a standard path between them. Scientists calculate material properties along this path, as seen in the x-axis of the phonon plot.
