Si diamond cubic primitive cell (Fd-3m, mp-149). 2 atoms, a=3.8493 Å, γ=60°. No free Wyckoff coordinates (8a). Non-magnetic, non-layered, covalent bonding. Discriminator test for Orb v3 symmetry erasure Mode 1/2 framework.
Cell + Ionic relaxation with Orb v3 conservative inf MPA; 0.03 eV/Å threshold; final energy = -10.8305 eV; energy change = -0.0019 eV; symmetry: Fd-3m → Fd-3m