We know that the transition metal oxides, like CuO are difficult to model using DFT and hence we use DFT+U with an appropriate U value to correctly describe the electronic structure of the transition metal oxides. You have suggested an U value of 4.0 for Copper in copper oxides in your previous papers like “A. Jain, G. Hautier, S.P. Ong, C. Moore, C.C. Fischer, K.A. Persson, G. Ceder, Formation Enthalpies by Mixing GGA and GGA+U calculations, Physical Review B, vol. 84 (2011), 045115”.
But, why have the oxides of copper been calculated with GGA and not with GGA+U here in the materials project?
I appreciate your help. Thanks!