[Wien] When to use (or not) onsite hybrid or +U?

[Peter Blaha]

No, I would not use DFT+U or onsite-hybrids for a metallic Mo (4d !!) 
SiB compound. The 4 d states are not localized enough.

I'd use SCAN for energetics, and maybe check for effects using a vdW 
functional (depends on the compound and structure).

Am 03.07.2021 um 16:30 schrieb Laurence Marks:
> Are there ways to test/calibrate what onsite hybrid or +U to use for 
> metals (i.e. compounds with states at EF)?
> 
> For context, I am doing some test calculations for Mo-Si-B compounds, 
> currently using PBE without spin. From my analysis of the energies there 
> are some Mo-B compounds which can be found in the ICSD database, but are 
> marginal in terms of the heat of formation and are not in 
> published phase diagrams. Unfortunately the phase diagram work to date 
> has not used the most modern characterization methods, so it may be 
> incomplete. IMHO if a structure/composition is in ICSD it should be real.
> 
> I know one way to calibrate on-site fractions is matching experimental 
> atomic positions, but none of these appear to be good enough (there are 
> fractional occupancies in some cases). Obviously matching band-gaps is 
> useless, even if I believed in this (which I don't).
> 
> Any suggestions?
> 
> -- 
> Professor Laurence Marks
> Department of Materials Science and Engineering
> Northwestern University
> www.numis.northwestern.edu <http://www.numis.northwestern.edu/>
> "Research is to see what everybody else has seen, and to think what 
> nobody else has thought" Albert Szent-Györgyi
> 
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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