A Bmab unit cell structure was used for all calculations of LaxPr4-xNi3O10 structures. Initial test calculations were performed for La4Ni3O10 in the higher symmetry I4/mmm structure, however, the structure relaxed to the Bmab structure upon full optimisation of the atomic positions and unit cell parameters. All distinct La/Pr orderings within the primitive Bmab unit cell structure (2 formula units) of LaxPr4-xNi3O10 for x = 0, 1, 2, 3 and 4 were enumerated using the CASM package, to predict the formation energy of phases on the convex energy hull . The atomic positions and unit cell parameters of all structures were fully optimised without symmetry constraints until the force on any atom fell below 0.05 eV Å -1 .