Updating the Materials Project VASP parameters

[esoteric-ephemera]

Problem

I've been working to systematically audit and benchmark a few parameters and POTCAR choices made by the Materials Project used in VASP calculations. I'm linking my recommendations for how these should be updated moving forward for longevity of the next round of MP calcs

This is in anticipation of recomputing the entirety of MP with r2SCAN and adding missing ICSD structures to MP. The bulk of the evidence is provided in that document, I'm happy to provide any further data for support.

Any changes to the MP flows are reflected in mp24 modules in this fork of atomate2

I've also been chatting with @mkhorton about this benchmarking effort, and he recommended performing a k-points check. I'm in the process of devising and running this check, but wanted to ensure this topic was broached prior to the upcoming foundation meeting, since there's enough in there to discuss now.

Also tagging in @matthewkuner, @janosh, @Andrew-S-Rosen, and @rkingsbury, who have all been involved in previous benchmark efforts, or this one.

[JaGeo]

Maybe unrelated: but are there any plans for comparing input and output structures of the optimization. I have seen a few issues (e.g., with solid iodine or bromine) where the structures did suffer from a DFT error after optimization. I would love an RMS value showing the difference in fractional coordinates or similar

[esoteric-ephemera]

Hi @JaGeo, happy to add a comparison for this. Are you mostly interested in cases where the spacegroup changes under relaxation (estimate of frequency, chemical spaces where this happens), or atoms with too-close/too-far separations after a relaxation?

Also for clarity: to isolate the effect of changing one parameter, most of the tests in this work involve statics for the actual comparison

[JaGeo]

I think also drastic position changes. But this might be harder to quantify than spacegroup

I think the ground state structure of solid iodine and bromine are currently not in MP anymore. The icsd IDs are matched to a structure that is far away from the experimental one, if I haven't oberlooked anything. Here, the space group stayed the same but positions changed drastically.
See here
https://next-gen.materialsproject.org/materials/mp-23153?formula=I2

Same for Br2

[Andrew-S-Rosen]

Thank you SO much for this writeup! Somewhat miraculously, I agree with everything here. I am looking forward to the switch being flipped! 😁

[Andrew-S-Rosen]

@esoteric-ephemera --- should you put the new input sets in pymatgen? Can atomate2 accept them yet?

[janosh]

excellent write up! very excited for the rerun. this will allow everyone who needs to maintain MP compatibility to start using up-to-date PSPs.

minor issue: fig. 9 seems to have wrong caption.

[Andrew-S-Rosen]

Any reason to include "LWAVE": True, "LCHARG": False in MP24GGARelaxSetGenerator, MP24GGAStaticSetGenerator, or MP24PBEsolPreRelaxSetGenerator if those are already being set by _BASE_MP24_RELAX_SET? I'd suggest removing them from the generators so we don't have things specified in multiple places.

[Andrew-S-Rosen]

I suppose I have one question. It seems that we are somewhat arbitrarily updating some POTCARs from https://www.nature.com/articles/s42254-023-00655-3. Is there any reason to not just go all-in for consistency and adopt the pseudopotentials used in https://www.nature.com/articles/s42254-023-00655-3? I see in the document it says we are taking a "don't fix what isn't broken approach," which is fair, but selecting 12 to update seems like it could introduce questions later on. Personally, I don't have a vote one way or another, but I am curious about the decision.

[mkhorton]

@Andrew-S-Rosen I believe the pseudopotentials in that paper are mostly the v54? I think the "don't fix what isn't broken approach" is typically wise, but if there is time for an across-the-board refresh, this would be it, especially if no regressions are observed.

[esoteric-ephemera]

@janosh:

minor issue: fig. 9 seems to have wrong caption.

Fig. 9 has the wrong figure! My bad - fixed.

@mkhorton @Andrew-S-Rosen:

@esoteric-ephemera --- should you put the new input sets in pymatgen? Can atomate2 accept them yet?

That will get migrated to pymatgen. First thing is to make the transition on the atomate2 side. Will do that this week.

Any reason to include "LWAVE": True, "LCHARG": False in MP24GGARelaxSetGenerator, MP24GGAStaticSetGenerator, or MP24PBEsolPreRelaxSetGenerator if those are already being set by _BASE_MP24_RELAX_SET? I'd suggest removing them from the generators so we don't have things specified in multiple places.

There's going to be a little rearrangement of the tags so those are mostly reminders for me. The fork is very much WIP

Is there any reason to not just go all-in for consistency and adopt the pseudopotentials used in https://www.nature.com/articles/s42254-023-00655-3?

Like you said, I'm trying only to reduce the errors to a level that's acceptable, and making changes to reflect that. Right now, it seems like that level of acceptable error due to the pseudopotential is ~2.5% (see Tb, where the MAPE in $V_0$ is reduced to 2.2% using the recommended POTCAR).

That being said, there is a practical issue to using all the recommended POTCARs. The O POTCAR has an ENMAX of 765.519 eV, which would require ENCUT $\gtrsim 920$ eV for relaxations of oxides (20% inflation of ENMAX). That's going to make high-throughput with r²SCAN impossible.

I agree with @mkhorton that it wouldn't hurt to know how the recommended POTCARs perform, excluding the O_h_GW potential

Also worth noting that it seems like maybe there's a mix of versions in the recommended potentials? Except for the Ba, Cs, Cu, He, Hf, and Rn POTCARs, all of the POTCAR SHAs indicate PBE_64 POTCARs. Those 6 match the PBE_54 hashes (could also be those were not updated at all going from 54 to 64).

[janosh]

Also worth noting that it seems like maybe there's a mix of versions in the recommended potentials? Except for the Ba, Cs, Cu, He, Hf, and Rn POTCARs, all of the POTCAR SHAs indicate PBE_64 POTCARs. Those 6 match the PBE_54 hashes (could also be those were not updated at all going from 54 to 64).

maybe @sudarshanv01 knows more about that?

[sudarshanv01]

Hi @janosh and @esoteric-ephemera, the changelog of the potentials which were updated are shown on the portal in the text near the release (or in log.message in the folder) . I am not sure which type of potential you are using for Ba (for example) - if it isn't the GW recommended version then I don't believe it has been updated. Cross checking against that list might be the easiest way to see what is updated.

[JaGeo]

@esoteric-ephemera should I add this discussion than as the second point on our agenda for the next meeting? In preparation, @esoteric-ephemera, we should probably send out the document in the mail. I will try to do this latest on next Monday.

Follow up question on mine before: will you start the new runs from the GGA results or from ICSD? This might influence the outcome quite a bit.

[esoteric-ephemera]

@JaGeo that'd be great if we set aside some time at the foundation meeting to discuss this. Hope to have some k-point density tests ready by then.

Follow up question on mine before: will you start the new runs from the GGA results or from ICSD? This might influence the outcome quite a bit.

This hasn't been decided yet, but I would imagine for any structure where the space group changed from the original input structure, we'd rerun from the original structure