 Zinc blende structure factor

The zinc blende structure consists of a face-centered cubic lattice with two species displaced by a quarter of the body diagonal. Its conventional-cell structure factor vanishes for mixed-parity Miller indices. For equal parity, $S_{\mathrm{FCC}}=4$: odd indices give $|F{|}^2=16(f_A^2+f_B^2)$ for real atomic scattering factors, even index sums divisible by four give $16(f_A+f_B{)}^2$, and sums congruent to two modulo four give $16(f_A-f_B{)}^2$. The last reflections diagnose sublattice scattering contrast. They vanish in the equal-factor diamond limit but need not vanish for a binary compound.