Dear Mohammed,
it's hard to give a general advice also because I didn't do many
calculation with rare earth elements. Just checking the headers of the
pseudos from the vlab side it seems both pseudos (LDA and GGA) have the
same states in valence (l_max=3, number_of_wfc=number_of_proj=8). Did
you try what they suggest on their side, i.e.:
"In some cases, defining orbital occupations (starting_ns_eigenvalue tag
in Quantum ESPRESSO) is essential in order to converge calculations."
Maybe this can help to achieve convergence!? Otherwise, it might also
help to ask them... Or try using the PAW pseudos from the pslibrary
without the f-states, e.g., Sm.pbe-spdn-kjpaw_psl.1.0.0.UPF (or the
ultrasoft one: Sm.pbe-spdn-rrkjus_psl.1.0.0.UPF).
And, of course, try what Karim and Ari said:
- increase ecutrho
- maybe ferromagnetic starting guess is wrong and you have to go for
anti-ferromagnetic
Regards
Thomas
On 30.11.2017 11:43, Mohammed Khalafalla wrote:
Dear Thomas,
Thank you very much for your comments and suggestions.
You are right the PBE pseudos from
http://www.vlab.msi.umn.edu/resources/repaw/index.shtml
<http://www.vlab.msi.umn.edu/resources/repaw/index.shtml> contains
f-states, but not the LDA ones (I noticed this simply by looking for
f-states within the pseudo files). So let me double check, shall I use
the LDA ones instead?
Thanks ones more.
Regards,
Mohammed
On 29 November 2017 at 11:24, Thomas Brumme
<[email protected] <mailto:[email protected]>>
wrote:
Dear Mohammed,
adding to the comments of Karim and Ari, I think that you should
consider using a pseudo without f-states - of course depending on
what you want to predict/calculate. In the end, you use DFT+U to
correct for the errors of DFT but putting the f-states into the
core is a first approximation to this idea. And the standard
ecutrho of 4 times ecutwfc is definitely not enough for PAW
potentials if the f shell is included.
Regards
Thomas
On 25.11.2017 20:16, Mohammed Khalafalla wrote:
Dear all,
I could not achieve scf convergence in Sm2La2O6 (the input file
is attached herewith). This was the case even after several
'restart' of the calculation with different pseudpotentials
specially for 'O' atom. I guess I used well tested PAW psedu for
rare earth from
http://www.vlab.msi.umn.edu/resources/repaw/index.shtml
<http://www.vlab.msi.umn.edu/resources/repaw/index.shtml>
I used recommended hubbard potentials and spin polarization, but
no change. Generally I found convergence in (Sm,O) system to be
difficult. Can you kindly let me know which parameter set-up
would determine successful convergence in (Sm,O) system?
Regards,
Mohammed A. H. Khalafalla (PhD)
Taibah University
KSA
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Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
Phillipp-Rosenthal-Strasse 31
04103 Leipzig
Tel: +49 (0)341 97 36456
email:[email protected] <mailto:[email protected]>
--
Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
Phillipp-Rosenthal-Strasse 31
04103 Leipzig
Tel: +49 (0)341 97 36456
email: [email protected]
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