I’m working with the phase diagrams that involve Mg and trying to do calculations that are compatible with the MP database.
I have been successful with reproducing MP compatible calculations for many other species and systems, however, I have trouble reproducing specifically the pure Mg endpoint. The MP database energy for mp-1056702 ends up at around -1.6 eV/atom (-1.6003 eV/atom), however, over many different attempts I always get around -1.49 eV/atom.
I am using pytmatgen to generate the input files (using the MPRelaxSet), I’ve taken care to use the correct pseudopotentials (matching the pymatgen hashes), and I use the MaterialsprojectCompability (but it does not adjust anything for pure Mg).
It may also be noteworthy that this endpoint was apparently found to be the lowest energy one in a recalculation 2020-09-02, whereas it seems previously a structure closer to the experimental ground state, mp-153 was the endpoint. However, also for that structure, I find the same discrepancy; MP reports -1.5909 eV/atom (so ~ -1.6 eV/atom just as the newer endpoint), and my own attempts at calculating this system also end up ~ -1.5 eV/atom. Another observation is that in an earlier archive of the mp database ( Materials Project Data ) the energy of mp-1056702 (the current endpoint of Mg ) has an energy of -1.4819 eV/atom ( which is close to what I calculated).
Is there a possibility that the input parameters for vasp calculations were changed in the custodian workflow? ( i am not using custodian for my workflow, so i might have missed this correction) ( What happens to the updated INCAR files mp/database wise when custodian corrects for an error? )
None of these calculations (mp-1056702 or mp-153) seems to be present in Nomad. Could you please consider sharing the raw output files from either of these to help me try to understand this discrepancy?
Thanks in advance!