No Stable Allotrope of Prometheum (Pr)

Materials Project
1

Hi,

When I search for Pr on materials project, all materials have energy above hull greater than 0.

When I do this api query, I get the same

el = 'Pr'

with MPRester() as mpr:
    docs = mpr.materials.summary.search(
        elements=[el],
        num_elements=1,
        is_stable=True,
    )
assert len(docs) == 1, f"Expected 1 summary document for {el}, got {len(docs)}"

I believe this is not expected behaviour, sorry if it is.

Best wishes,

Tom

2

Thanks for catching this, @Thomas_Warford. This looks like an unintentional effect of the mixing scheme used to align the (already mixed+corrected) PBE GGA/+U hulls and the r2SCAN hull:

from mp_api.client import MPRester

with MPRester() as mpr:
    thermo_docs = {
        k : mpr.materials.thermo.search(chemsys = ["Pr"],thermo_types=[k])
        for k in ("R2SCAN", "GGA_GGA+U_R2SCAN")
    }

by_ehull = {
    k : sorted(v, key = lambda doc : doc.energy_above_hull) for k, v in thermo_docs.items()
}

print(f"r2SCAN only hull ({by_ehull["R2SCAN"][0].material_id}): {by_ehull["R2SCAN"][0].energy_above_hull}")
print(f"Default MP hull ({by_ehull["GGA_GGA+U_R2SCAN"][0].material_id}): {by_ehull["GGA_GGA+U_R2SCAN"][0].energy_above_hull}")

>>> r2SCAN only hull (mp-97): 0.0
>>> Default MP hull (mp-97): 0.008044545

Which tells us that internally (the calculations without any corrections) the thermodynamic hulls make sense, but something is going wrong in the corrections.

We’ll be transitioning to r2SCAN-only data (without any corrections) so this shouldn’t be an issue, but I’ll look into why this is happening in the meantime

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