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<p class="MsoNormal">Could you please be more specific on this? </p>
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<p class="MsoNormal" style="border:none;padding:0in"><b>From: </b><a href="mailto:Michal.Husak@vscht.cz">Husak Michal</a><br>
<b>Sent: </b>Saturday, January 30, 2021 11:39 PM<br>
<b>To: </b><a href="mailto:users@lists.quantum-espresso.org">Quantum ESPRESSO users Forum</a><br>
<b>Subject: </b>Re: [QE-users] crystal definition</p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Forget this method.<br>
Get a CIF file for the structure you want to stady and<br>
use the space group based crystal definition ...<br>
________________________________<br>
From: users <users-bounces@lists.quantum-espresso.org> on behalf of valeria arteaga muñiz <valitzelar@hotmail.com><br>
Sent: Sunday, January 31, 2021 5:26:37 AM<br>
To: users@lists.quantum-espresso.org<br>
Subject: [QE-users] crystal definition<br>
<br>
Hello everyone.<br>
<br>
I have been working for a couple of months with quantum espresso and still there are some things that get me confused. I hope you can help me.<br>
If we wanted to define a BCC crystal (lets say) we could make use of the ibrav=3 parameter. With this, we would have a bcc structure with one atom per cell (?). I don’t know how can that be possible if the bcc cell is supposed to have two atoms per cell (1/8
contribution of 8 corner atoms + 1 contribution of a middle atom). When I use xcrysden for visualization just setting ibrav =3, I get the complete bcc structure.<br>
<br>
I also have tried to create my bcc crystal from scratch using ibrav=0 and placing the atomic positions at the corner and other atom at 0.5 0.5 0.5 (center), which leads to 2 atoms per unit cell. When I make scf calculations for this case I get around twice
the total energy I get in previous case (using ibrav=3). I wonder what is the correct way to use this.<br>
<br>
<br>
Thanks for your clarifications,<br>
Valeria<br>
<br>
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