“…While most of the symmetryunique oxygen atoms are shared between two tetrahedra, two are not: the multiplicity-four O1 site is connected only to a single T site, and the multiplicity-four O3 site is shared between three T sites (Kahlenberg, Hejny & Kru ¨ge, 2019). CAZO has been reported to exhibit tetrahedral tilting under high pressure (Kahlenberg, Hejny & Kru ¨ge, 2019), and the isostructural Ca 3 Al 4 MnO 10 compound might be expected to do the same (Kahlenberg, Albrecht et al, 2019). In order to include contributions from all special k vectors, we consider a P1-symmetry supercell of the Pbcm-symmetry parent cell with relative basis {(2, 0, 0), (0, 2, 0), (0, 0, 2)}, which is eight times larger than the parent, providing N pivot = 160 T-site SUPAs and N shared = 320 oxygen SUSAs (including the O1 sites).…”