The variation in the unit cell volume was calculated for each structure as shown in Fig. . An approximately linear increase in the unit cell volume is observed from compositions of x=0 to x=4 in LaxPr4-xNi3O10, which is consistent with the experiment (Fig. ). A slightly larger unit cell volume is predicted computationally compared to the experiment, as is commonly observed with DFT(+U) calculations using the PBE functional. For all configurations studied, it can be seen from Fig. that the change in the chemical composition (x) has a bigger influence on the unit cell volume than the La/Pr ordering at fixed composition.