[QE-users] Issue on LDA+U test calculation on Gd

[Timrov Iurii]

Dear Giovanni,


> I’ve browsed the PW/src/offset_atom_wfc.f90 routine. It seems (that is what I have understood) that while in Modules/set_hubbard_l.f90 it is set
hubbard_l = 3  for that atomic species, in the pseudo potential file (see e.g. http://www.quantum-espresso.org/upf_files/Gd.pbe-spdn-kjpaw_psl.1.0.0.UPF)
the l=3 wave function is not found.
> The atomic configuration of Gd is Xe 4f7 5d1 6s2.


I would try to use the recommended pseudo from the SSSP library. For Gd, the recommended pseudo is from the Wentzcovitch library. I do not know if f electrons are included, though, one has to check.


> i) it is sufficient to solve the problem or wrong to set hubbard_l = 2 in Modules/set_hubbard_l.f90?
> Should the Hubbard U be more important for those l=3 electronic states than for l=2 states?

4f and 5d channels are both partially occupied, so I presume that one should try to put U on both channels (but this is currently not possible in QE). So, by default the f channel is used for Gd in QE. It is not obvious (at least for me) though whether putting U on 5d would be important for Gd. One should investigate the PDOS and see where the contributions from 4f and 5d are located (at the LDA or GGA level), and on the basis of this information decide to which channel U should be applied.

> ii) more importantly (sorry for the basic question, I’v never considered systems with f electrons): why f electrons are not considered in the pseudo file?

You have chosen the PP which indeed does not contain the f states. But in the PSlibrary there are pseudos of Gd containing f electrons, so you can try those. It is better to ask Andrea Dal Corso why f states were not included in some versions of pseudos.

Best regards,
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
http://people.epfl.ch/265334
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Giovanni Cantele <giovanni.cantele at spin.cnr.it>
Sent: Monday, February 10, 2020 4:51:11 PM
To: Quantum ESPRESSO users Forum
Subject: [QE-users] Issue on LDA+U test calculation on Gd

Dear all,

I’m trying to make a test calculation of a crystal containing the Gd atom. I use the DFT+U scheme.
However, as the program starts, I’ve immediately facing the following error:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     Error in routine offset_atom_wfc (2):
     wrong offset
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


I’ve browsed the PW/src/offset_atom_wfc.f90 routine. It seems (that is what I have understood) that while in Modules/set_hubbard_l.f90 it is set
hubbard_l = 3  for that atomic species, in the pseudo potential file (see e.g. http://www.quantum-espresso.org/upf_files/Gd.pbe-spdn-kjpaw_psl.1.0.0.UPF)
the l=3 wave function is not found.
The atomic configuration of Gd is Xe 4f7 5d1 6s2.

So my question is:

i) it is sufficient to solve the problem or wrong to set hubbard_l = 2 in Modules/set_hubbard_l.f90?
ii) more importantly (sorry for the basic question, I’v never considered systems with f electrons): why f electrons are not considered in the pseudo file?
Should the Hubbard U be more important for those l=3 electronic states than for l=2 states?

Thanks for any answer you could provide.

Giovanni



--

Giovanni Cantele, PhD

CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy

e-mail: giovanni.cantele at spin.cnr.it<mailto:giovanni.cantele at spin.cnr.it>
            gcantele at gmail.com<mailto:gcantele at gmail.com>
Phone: +39 081 676910
Skype contact: giocan74
Web page: https://sites.google.com/view/giovanni-cantele

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