Since the BC8 structure is characterised by even membered rings, is is
possible to construct a diatomic analogue in which only unlike species
are bonded. However the 8 atom body centered cell is not appropriate
for this. If the BC8 structure is considered to be simple cubic with 16
atoms in the unit cell then 2 species can be arranged with only unlike
species bonding. It follows that this structure has lower symmetry -
primitive cubic, with point group symmetry P 
and unlike BC8 it
does not have a centre of inversion. The effect of this is that the
structure can be fully described by two internal parameters, 
,
where s=1,2 labels the species. Curiously, the lengths of the bonds
depend only on one parameter, 
. The distance to the nearest
non-bonded neighbour, 
, is species dependent. These lengths can be
expressed in terms of the lattice parameter and by
Like the BC8 structure in Group IV elements, the SC16 structure with its distorted tetrahedral units is a tractable complex crystal model of amorphous III-V semiconductors having short range disorder and zero like species bonding. Studies of the structural, optical and electronic properties of GaAs in the SC16 structure have been made using an empirical pseudopotential method in an attempt to investigate the amorphous phase[66].