Discrepancies in Elastic Modulus Data Between Legacy and Next-Gen Materials Project Databases

Materials Project
1

Hello,

I recently came across a paper where the authors cited elastic modulus data from the Materials Project database. However, when I attempted to verify this information, I noticed discrepancies between the data I retrieved and the values reported in the paper. Upon further investigation, I found that the elastic modulus for some materials seems to have changed in the Materials Project database.

For example, for material mp-1639 BN, the legacy data available at Legacy Materials Project mp-1639 shows a Shear Modulus (GVRH) of 374 GPa and a Bulk Modulus (KVRH) of 408 GPa. However, the updated data at Next-Gen Materials Project mp-1639 shows a Bulk Modulus (Voigt-Reuss-Hill) of 374 GPa and a Shear Modulus (Voigt-Reuss-Hill) of 379 GPa.

An even more extreme example is mp-3830 NiAsS. In the legacy database Legacy Materials Project mp-3830, the Shear Modulus (GVRH) is listed as 59 GPa and the Bulk Modulus (KVRH) as 109 GPa. However, in the updated database Next-Gen Materials Project mp-3830, the Bulk Modulus (Voigt-Reuss-Hill) is 12364 GPa and the Shear Modulus (Voigt-Reuss-Hill) is 7407 GPa.

Could you please explain what led to the updates in the elastic modulus values for these materials? Are these updated modulus values reliable? Additionally, is there a log or documentation where I can find detailed information about these changes?

Thank you for your assistance.

2

@GaugeField we identified a number of issues with some of the elastic data a while back, and in response rewrote some of the workflow to fix those. This included a full recompute of the data. In most cases, the values should me more accurate than legacy. Recently, we have identified a few entries with problems and are working on a fix for them. I will add mp-3830 to the list of flagged materials on our end.

– Jason