[QE-users] Re :Re: Inquiry Regarding Crystal Structure Discrepancy in Quantum Espresso

Mon Jan 1 13:04:44 CET 2024

Thank you so much for your explanation.

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  Le sam., déc. 30, 2023 à 20:35, Giovanni Cantele<giovanni.cantele at spin.cnr.it> a écrit:   As I infer from the input you sent me, if you take atomic positions, designed to fill the unit cell of a simple tetragonal crystal and use the same to fill the sites of a body centered tetragonal lattice, you'll definitely obtain two different structures, one should worry in the case they look equal!
What you should observe is that your atomic positions are "redundant" in that if instead of replicating them on the sites of a simple tetragonal lattice you replicate a fraction of them on the sites of a body centered lattice, then the two resulting structures are the same. In this case, since the st primitive cell has twice the volume of a bct primitive cell, you should halve the positions (of course removing the ones equivalente by a translation of the bct lattice), then ibrav=7 will definitely work.BEWARE: your positions are in crystal units. That means they are expressed in units of a1,a2,a3 of the st lattice. As such, besides halving the number of atoms, you have to change also the positions of the remaining ones, if you keep crystal as units (because a1',a2',a3' of bct are different from a1,a2,a3 of st), otherwise convert them in Angstrom first.
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
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: https://sites.google.com/view/giovanni-cantele/home

Il giorno sab 30 dic 2023 alle ore 17:03 houssam eddine hailouf <h.hailouf at yahoo.com> ha scritto:

Please sir if I can proceed my calculations with ibrav =6 and if this state is correct " 7 is for body centered tetragonal. 6 is for primitive one"
My problem,but when I write Ibrav =7 and I use xcrysden to visualize the structure I found other structure and when I write Ibra =6 I find the relevant structure. 
Sincerely Hailouf 

  Le sam., déc. 30, 2023 à 16:20, Giovanni Cantele<giovanni.cantele at spin.cnr.it> a écrit:   and what is the file with ibrav=7 that gives you incorrect results?GC
-- 

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
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: https://sites.google.com/view/giovanni-cantele/home

Il giorno sab 30 dic 2023 alle ore 16:07 houssam eddine hailouf <h.hailouf at yahoo.com> ha scritto:

Hi dear Giovanni 

Please find my input file attached below such as the system under consideration is body-centered tetragonal crystal structure (I41md), but when i display the crystal structure with ibrav= 7 i get wrong crystal structure but it's fine with ibrav=6.
SincerelyHailouf
   Le samedi 30 décembre 2023 à 14:38:13 UTC+1, Giovanni Cantele <giovanni.cantele at spin.cnr.it> a écrit :  

 Dear Hailouf,
I think it is not easy to help you with the information you provided.1) What do you mean with "an incorrect crystal structure"? Is Quantum-ESPRESSO giving a structure you do not expect or the calculation fails for some other reason? In the case, what is the "error" provided by the code?2) In ibrav=6 produces the "correct structure", then your structure is simple tetragonal? Or you are trying to reproduce a body-centered tetragonal structure using a simple tetragonal unit cell?
With some more detail (and/or input/output files), maybe a more helpful answer could be issued.
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
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: https://sites.google.com/view/giovanni-cantele/home

Il giorno sab 30 dic 2023 alle ore 14:05 houssam eddine hailouf via users <users at lists.quantum-espresso.org> ha scritto:

Dear Quantum Espresso Group,
I am currently studying systems within the body-centered tetragonal structure. I've encountered an issue where setting ibrav = 7 yields an incorrect crystal structure, while using ibrav = 6 produces the correct structure, and calculations proceed smoothly. Could you provide any insights or explanations regarding this situation?
Thank you,Hailouf houssam Materials Science and Informatics Laboratory, Djelfa algerie._______________________________________________
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_______________________________________________
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-- 

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
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: https://sites.google.com/view/giovanni-cantele/home

Il giorno sab 30 dic 2023 alle ore 14:05 houssam eddine hailouf via users <users at lists.quantum-espresso.org> ha scritto:

Dear Quantum Espresso Group,
I am currently studying systems within the body-centered tetragonal structure. I've encountered an issue where setting ibrav = 7 yields an incorrect crystal structure, while using ibrav = 6 produces the correct structure, and calculations proceed smoothly. Could you provide any insights or explanations regarding this situation?
Thank you,Hailouf houssam Materials Science and Informatics Laboratory, Djelfa algerie._______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users at lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users

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