Ehull mismatch

Materials Project
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3

Can you take a look at the answers to this question and ensure that you’re looking at the formation energies after applying corrections?

mp-3308927 specifically is a compound from the GNoME dataset which has certain use restrictions. Because of these use restrictions, we haven’t yet released thermodynamic data for all of the GNoME materials.

If you want to build the phase diagrams for these, you can use the python API client:

from mp_api.client import MPRester
from pymatgen.entries.computed_entries import ComputedEntry
from pymatgen.analysis.phase_diagram import PhaseDiagram

with MPRester() as mpr:
    t = mpr.get_entries_in_chemsys("Ta-Nb-O",additional_criteria={"thermo_types": ["R2SCAN"]})
    gnome_doc = mpr.materials.summary.search(material_ids=["mp-3308927"])[0]

entries = t + [
    ComputedEntry(
        composition=gnome_doc.composition,
        energy=gnome_doc.uncorrected_energy_per_atom*gnome_doc.composition.num_atoms,
        entry_id=gnome_doc.material_id.string,
        parameters = {
            "run_type": "R2SCAN",
        },
        data = {
            "material_id": gnome_doc.material_id.string,
        }
    )
]
pd = PhaseDiagram(entries)
pd.get_plot()

If you want to use the full hull, then change “R2SCAN” to “GGA_GGA+U_R2SCAN”, and make sure you add these lines before creating the phase diagram:

from pymatgen.entries.mixing_scheme import MaterialsProjectDFTMixingScheme
MaterialsProjectDFTMixingScheme().process_entries(entries)
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