| Structural type | A4 |
| Common name | diamond |
| Definition | ideal 4-coordinated lattice |
| Prototype | C |
| Pearson symbol | cF8 |
| Space group | 227 Fd-3m Oh7 |
| Chemical formula | A |
| Bonding | covalent |
| Atomic positions | A (8a) 1/8 1/8 1/8 (origin is at the inversion point) |
| Coordination | 4t |
| PDB files | A4 |
| Substructures | B3 |
| Substances | IV elements (see the table below) |
Can be constructed as two fcc lattices shifted along the diagonal on 1/4, that is zincblende B3 lattice with identical atoms. It can also be considered as bcc lattice with vacancies (in pdb they are marked by O), which form the second diamond sublattice of the bcc lattice.
Packing factor δ=sqrt(27/128)≈.46.
| A | a | comment |
|---|---|---|
| C | 3.5669 | stable at high pressure |
| Si | 5.431 | |
| Ge | 5.6575 | |
| α-Sn | 6.5043 | T<286K |