A5, beta-tin

Structural typeA5
Common namebeta-tin
Prototypeβ-Sn
Pearson symboltI4
Space group141 I41/amd D4h19
Chemical formulaA
Bondingmetallic-covalent
Atomic positions  A (4a)  0  3/4  1/8 (origin is at the inversion point)
Coordination4+2+4 for c/a>2/sqrt(15)
2+4+4 for c/a<2/sqrt(15)
PDB filesA5 (ideally packed), 2 unit cells
Parametersc/a≥0.52
Special casesbest packing for c/a=2/sqrt(15) with δ=8*sqrt(2)/15≈0.75
Superstructuresdia for c/a=sqrt(2)
Substanceshigh-pressure metallic phase of IV elements