Receipts for the A-cation site-preference control: CHGNet energies of the three two-formula-unit arrangements in CoFe2O4, ZnFe2O4, and MgAl2O4.
A machine-learning potential ranked all 78 spinel orderings. Its control says the ranking is backwards.
CHGNet statics on one representative of each CoFe2O4 cation-ordering class fail the inverse-spinel known-answer control, so the ground-state question goes back on the shelf.