[QE-users] QE-7.1 and DFT+U

[Mahmoud Payami Shabestari]

Dear Iurii,




You argue that since O atom is not magnetic, the starting_magnetization for 
that atom is taken to be zero.
I would like to attract your attention to the work:


https://arxiv.org/abs/2108.12758


in which it is shown that the GS of UO2 is obtained for non-zero 
starting_magnetization of O-atom.
I have to check the results from QE-7.1 of my inputs (of course in new 
syntax) of the above work to see if I get the same results. Otherwise, the 
occupations were wrongly dependent on the starting_magnetization of O-atoms, 
and now it is bug-fixed. By "hard-coded" I do not understand what you mean.
Thank you again.


Best regards,
Mahmoud










From: Iurii TIMROV via users <users at lists.quantum-espresso.org>
To: Mahmoud Payami Shabestari <mpayami at aeoi.org.ir>, "Quantum ESPRESSO users 
Forum" <users at lists.quantum-espresso.org>
Date: Wed, 29 Jun 2022 11:44:03 +0000
Subject: Re: [QE-users] QE-7.1 and DFT+U



Dear Mahmoud,




> Explicitly, the starting_magnetization for O is removed in the new one. 
Does it mean the default value is still zero or the code searches for a 
better starting magnetization?




O atoms are nonmagnetic so that's why starting_magnetization for O was 
removed. 




> But, comparing the results from qe-7.1 and qe-6.7, one notices significant 
changes in the input and outputs of feo_user_ns files.




FeO is metallic in DFT while it is insulting in nature. The difference 
between the new and old behaviour of QE is the starting occupations of the 
Fe-3d manifold. In older versions of QE (before 7.1) the starting 
occupations are hard-coded to be 6 (see PW/src/tabd.f90) while in QE7.1 the 
starting occupations are read from the pseudopotential (in this particular 
example it is 7). It turns out that in this example different starting 
occupations for Fe-3d states lead to the convergence to different metallic 
ground states of FeO, but in any case both are wrong ground states (one 
needs +U and to use starting_ns_eignevalue to open a gap and thus obtain the 
correct ground state). But if you want to restore the old behaviour of QE in 
the new version (i.e. 7.1) you need to specify in the input the new keyword 
Hubbard_occ(1,1) = 6.0 and Hubbard_occ(2,1) = 6.0 (because you have Fe1 and 
Fe2) - in this case the code reads the starting occupations from the input 
and not from the pseudopotential.  




Greetings,

Iurii




--
Dr. Iurii TIMROV
Senior Research Scientist
Theory and Simulation of Materials (THEOS)
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Mahmoud 
Payami Shabestari via users <users at lists.quantum-espresso.org>
Sent: Wednesday, June 29, 2022 1:16:53 PM
To: users at lists.quantum-espresso.org
Subject: [QE-users] QE-7.1 and DFT+U


Dear QE developers,


Hi.
In the new release QE-7.1, I investigated through the example08 of PW, the 
example of FeO.
In the release-notes, Incompatible changes, line 3, it is mentioned that 
"input syntax" is changed.
But, comparing the results from qe-7.1 and qe-6.7, one notices significant 
changes in the input and outputs of feo_user_ns files.
Explicitly, the starting_magnetization for O is removed in the new one. Does 
it mean the default value is still zero or the code searches for a better 
starting magnetization?
Any comments is highly appreciated.


With best regards,
Mahmoud Payami
NSTRI, AEOI, Tehran, Iran


Email: mpayami at aeoi.org.ir
Phone: +98 (0)21 82066504


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