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Bond-centred inversion in diamond cubic gives one inversion centre at the midpoint of a nearest-neighbor bond:Mark its projected point $(1/8,1/8)$ and label its height $z/a=1/8$. Inversion about this point sends $\mathbf{r}$ to $(1/4,1/4,1/4)-\mathbf{r}$. It exchanges the two identical FCC sublattices and therefore preserves the crystal. An individual atom at the chosen origin is not an inversion centre.