Re: [QE-users] U calculation, different projection type

Wed, 26 Aug 2020 03:51:56 -0700

Dear Iurii, Lorenzo
 
Thanks for prompt reply.
 
I'll compare properties of the system I'm investigating, using both projection types.
 
I have more general question - it seems that whole idea to use U correction if the system under study is metallic in plain DFT, and using DFT+U brings the system to the correct ground state. The system I study is a MOF with Mn atoms. It is already insulating (band gap ~1.8 eV from DFT), but I guess U correction will increase band gap even more. I wonder if I really need to use U correction. Unfortunately, the material is not well studied, and experimental paper does not provide much information about electronic structure - just geometry (cif) and ferroelectric properties are reported.
 
Thanks,
 Sergey Lisenkov
 
 
 
26.08.2020, 12:14, "Timrov Iurii" <[email protected]>:

Dear Sergey,

 

As Lorenzo said, yes this is expected. Ab initio U depends on the Hubbard manifold, i.e. which projector functions are used (e.g. atomic, orthogonalized atomic, Wannier functions, you name it). So it is absolutely important to report in papers which projector functions were used for the calculation of U. In particular, this is why one should be very careful when comparing U values from different papers. There are also other factors that influence the value of U (pseudopotentials, oxidation state, functional, one-shot or self-consistent calculation). We have some papers in preparation on this topic, which hopefully would clarify a bit more these points. You can also check this web page: http://theossrv1.epfl.ch/Main/DFTHubbard

 

Greetings,

Iurii

 

--
Dr. Iurii TIMROV
Postdoctoral Researcher
STI - IMX - THEOS and NCCR - MARVEL
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
From: users <[email protected]> on behalf of Lorenzo Paulatto <[email protected]>
Sent: Wednesday, August 26, 2020 10:59:13 AM
To: [email protected]
Subject: Re: [QE-users] U calculation, different projection type
 
> Is it expected behavior?

Yes,
kind regards

> Thanks,
>   Sergey

--
Lorenzo Paulatto - Paris
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