Update deml_elementdata.py

[zzccchen]

Update the electric_pol item

Update the electric_pol item in the properties dictionary based on the latest literature [1], especially the rare earth element data.

[1] Schwerdtfeger, Peter, and Jeffrey K. Nagle. "2018 Table of static dipole polarizabilities of the neutral elements in the periodic table." Molecular Physics 117.9-12 (2019): 1200-1225. https://doi.org/10.1080/00268976.2018.1535143

• Fixed an exception where NaN appears when calculating deml electric_pol when rare earth elements such as Ce appear in the composition.

TODO

• Past calculation results may not be reproducible on deployed devices.

[ml-evs]

Has the source data changed in this PR? I see that many existing values also update (e.g., Li goes from 24.33 to 24.31896322). It might be good to add this as a new dataset and keep the old one for posterity too.

[zzccchen]

I agree with your idea. It may be more appropriate to add a new feature to the features of the "deml" preset, such as "electric_pol_2019".

[ml-evs]

I agree with your idea. It may be more appropriate to add a new feature to the features of the "deml" preset, such as "electric_pol_2019".

That would be great if you're willing to do that!