<div dir="ltr"><div dir="ltr">On Thu, Dec 23, 2021 at 3:51 PM Husak Michal <<a href="mailto:Michal.Husak@vscht.cz">Michal.Husak@vscht.cz</a>> wrote:</div><div dir="ltr"><br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">We can probably decipher what is QE doing internally<br></blockquote><div><br></div><div>no need to do that. You have in output the primitive cell and atoms in the primitive cell. You find what you call the "standard" cell, presumably the corresponding "P" one (the primitive cell is "F", "I", whatever), n times larger (n=2 or 4) than the primitive cell. Then you look for n lattice points in the primitive cell that are not lattice points of the "standard" cell. Or at least, this is my understanding of your problem<br></div><div><br></div><div>Paolo<br></div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
________________________________<br>
From: users <<a href="mailto:users-bounces@lists.quantum-espresso.org" target="_blank">users-bounces@lists.quantum-espresso.org</a>> on behalf of Paolo Giannozzi <<a href="mailto:p.giannozzi@gmail.com" target="_blank">p.giannozzi@gmail.com</a>><br>
Sent: Thursday, December 23, 2021 10:25:42 AM<br>
To: Quantum ESPRESSO users Forum<br>
Subject: Re: [QE-users] QE automatically converge centered cell to primitive ?<br>
<br>
I am not sure I understand what you mean. If you supply the structure and atomic positions via the space group and Wyckoff positions, QE generates the primitive (smallest) unit cell and corresponding lattice. QE does not change the symmetry or the structure by its own will, unless there is a bug for your specific case. If you prefer the so-called "conventional" unit cell, you need to consider the atoms that are in the conventional unit cell but not in the primitive one.<br>
<br>
Paolo<br>
<br>
On Wed, Dec 22, 2021 at 5:07 PM Michal Husak <<a href="mailto:Michal.Husak@vscht.cz" target="_blank">Michal.Husak@vscht.cz</a><mailto:<a href="mailto:Michal.Husak@vscht.cz" target="_blank">Michal.Husak@vscht.cz</a>>> wrote:<br>
Hi<br>
<br>
We had entered inside QE a structure described by fractional<br>
coordinates (asymmetric unit cell)<br>
and space group (C 2/c ) ....<br>
From the output we see QE had itself transformed the structure to<br>
another space group and unit cell<br>
(probably P 2/c triclinic system) to get speed of calculation ....<br>
<br>
Question:<br>
- does QE anywhere mention, this transformation was done ?<br>
- does it anywhere give the used transformation matrix ?<br>
<br>
We simply need to reconstruct from the QE the atom positions<br>
corresponding to the original CIF data ....<br>
<br>
Michal Husak<br>
UCT Prague<br>
<br>
<br>
<br>
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--<br>
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br>
Univ. Udine, via delle Scienze 206, 33100 Udine, Italy<br>
Phone +39-0432-558216, fax +39-0432-558222<br>
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</blockquote></div><br clear="all"><br>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br>Univ. Udine, via delle Scienze 206, 33100 Udine, Italy<br>Phone +39-0432-558216, fax +39-0432-558222<br><br></div></div></div></div></div></div>