Possible issue with Co oxide structures

Dear all,

I wanted to discuss the possibility of an issue with some Co oxides structures that are reported in the Materials Project.

mp-19079 for instance, is reported as cubic (space group Fm-3m) while the detailed structure is not: the conventional lattice is hexagonal (alpha=beta=90°, gamma=120°), but the primitive lattice has a=b=c, alpha=beta=gamma=60.33° which is pretty close to being cubic so maybe this is only an issue with tolerances (though I would argue that the angles should be exactly 60° since the ICSD entries are exactly cubic). In any case the conventional cell should, in my opinion, correspond to the cubic structure and space group.
mp-22408 has the same issue. If this behavior is not expected, I have no clue whether this is happening only to those 2 systems or if others are impacted as well.

Note that this issue has been reported here: https://matsci.org/t/wrong-structures-for-coo/48202 but not addressed so far.

Thanks for all the great work,


Hi Guillaume.

Do you get the same issue if you download the structures from the MPRester?

Hi Francesco,

Yes, I get the “hexagonal” structure.

Hi all, any clue about this?