<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none"><!--P{margin-top:0;margin-bottom:0;} --></style>
</head>
<body dir="ltr" style="font-size:12pt;color:#000000;background-color:#FFFFFF;font-family:Calibri,Arial,Helvetica,sans-serif;">
<p>Dear Paolo,</p>
<p><br>
</p>
<p>I am not sure to understand. The documentation on ibrav=2 shows the following cell convention:</p>
<pre style="margin-bottom: -1em;">2 cubic F (fcc)
v1 = (a/2)(-1,0,1), v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0)<br><br>which corresponds to a fcc primitive cell and the position input that I provide corresponds to this cell. <br>How could the position input be in simple cubic while the cell input is a primitive cell ?<br>Thanks for your prompt reply.<br><br>Cheers,<br><br>Felix <br><br><br></pre>
<p><br>
</p>
<div id="Signature">
<div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0">
<font size="3" color="black"><span dir="ltr" style="font-size:12pt; background-color:white"><font size="1"><span style="font-size:13.32px">F</span></font></span></font><font size="3" color="black"><span dir="ltr" style="font-size:12pt; background-color:white"><font size="1"><span style="font-size:13.32px">élix
Musil </span></font><br>
<font size="1"><span style="font-size:13.32px">Doctoral Assistant - Ph.D Student</span></font><br>
<br>
<font size="1"><span style="font-size:13.32px">EPFL STI IMX COSMO</span></font><br>
<font size="1"><span style="font-size:13.32px">LABORATORY OF COMPUTATIONAL SCIENCE AND MODELLING</span></font><br>
<font size="1"><span style="font-size:13.32px">Institute of Materials Science and Engineering</span></font><br>
<font size="1"><span style="font-size:13.32px">MXG 319</span></font><br>
<font size="1"><span style="font-size:13.32px">Station 12</span></font><br>
<font size="1"><span style="font-size:13.32px">CH-1015 Lausanne</span></font><br>
<font size="1"><span style="font-size:13.32px">Switzerland</span></font><br>
<br>
<font size="1"><span style="font-size:13.32px">E-mail: felix.musil@epfl.ch</span></font><br>
<font size="1"><span style="font-size:13.32px">http://cosmo.epfl.ch/</span></font></span></font></div>
</div>
<div style="color: rgb(33, 33, 33);">
<hr tabindex="-1" style="display:inline-block; width:98%">
<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" color="#000000" face="Calibri, sans-serif"><b>De :</b> pw_forum-bounces@pwscf.org <pw_forum-bounces@pwscf.org> de la part de Paolo Giannozzi <p.giannozzi@gmail.com><br>
<b>Envoyé :</b> vendredi 15 septembre 2017 21:31<br>
<b>À :</b> PWSCF Forum<br>
<b>Objet :</b> Re: [Pw_forum] ibrav=2 and space_group=202: input coordinate misunderstood</font>
<div> </div>
</div>
<div>
<div dir="ltr">
<div>
<div>If I remember correctly Wyckoff positions for fcc crystals are in simple cubic axis (the so-called "conventional" unit cell), while the atom you are looking at in the output is in crystal axis of the fcc cell. If you look at the same atom in cartesian
axis:<br>
1 Si tau( 1) = ( -0.6943213 0.4949861 0.5050079 )<br>
</div>
it has the same x,y,z positions as the input one, displaced by (1.5, 0.0, 0.5)<br>
<br>
</div>
Paolo<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, Sep 15, 2017 at 6:52 PM, Musil Félix <span dir="ltr">
<<a href="mailto:felix.musil@epfl.ch" target="_blank">felix.musil@epfl.ch</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex; border-left:1px #ccc solid; padding-left:1ex">
<div dir="ltr" style="font-size:12pt; color:#000000; background-color:#ffffff; font-family:Calibri,Arial,Helvetica,sans-serif">
<span dir="ltr" style="font-size:12pt; background-color:white">
<div style="margin-top:0; margin-bottom:0">Dear QE developers,</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0">I am running the following input file and the resulting output has changed the non equivalent scaled atomic coordinates (see highlighted in yellow). I compared with space group 224 with ibrav=1 and these scaled coordinates
do match. Is there a reason for this particular behavior ? <br>
</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0">Please find attached an input file to reproduce this behavior.<br>
</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0">Cheers,</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0">Felix Musil<br>
</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0">QE INPUT:</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0">&CONTROL<br>
calculation = "scf"<br>
outdir = "./out/"<br>
prefix = "qe"<br>
pseudo_dir = "/scratch/musil/run_qe/pseudo/<wbr>SSSP_acc_PBE/"<br>
restart_mode = "from_scratch"<br>
verbosity = "high"<br>
wf_collect = .false.<br>
/<br>
&SYSTEM<br>
ecutrho = 40.00000<br>
ecutwfc = 10.00000<br>
ibrav = 2<br>
nat = 1<br>
nbnd = 57<br>
ntyp = 1<br>
occupations = "smearing"<br>
smearing = "cold"<br>
degauss = 0.010000<br>
space_group = 202<br>
A = 11.740480817708141<br>
/<br>
&ELECTRONS<br>
conv_thr = 0.10000000<br>
/<br>
ATOMIC_SPECIES<br>
Si 28.0855 Si.pbe-n-rrkjus_psl.1.0.0.UPF<br>
ATOMIC_POSITIONS crystal_sg<br>
Si <span style="background-color:yellow">0.80567873 0.49498614 0.00500792</span></div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0">QE OUTPUT:</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0"> Program PWSCF v.6.1 (svn rev. 13369) starts on 15Sep2017 at 18:33: 4<br>
<br>
This program is part of the open-source Quantum ESPRESSO suite<br>
for quantum simulation of materials; please cite<br>
"P. Giannozzi et al., J. Phys.:Condens. Matter 21 395502 (2009);<br>
URL <a href="http://www.quantum-espresso.org" target="_blank">http://www.quantum-espresso.<wbr>org</a>",<br>
in publications or presentations arising from this work. More details at<br>
<a href="http://www.quantum-espresso.org/quote" target="_blank">http://www.quantum-espresso.<wbr>org/quote</a><br>
<br>
Parallel version (MPI), running on 8 processors<br>
R & G space division: proc/nbgrp/npool/nimage = 8<br>
Reading input from /scratch/musil/data/check_<wbr>input_errors/sg_202-f_0-0/<a href="http://qe.in" target="_blank">qe.<wbr>in</a><br>
.</div>
<div style="margin-top:0; margin-bottom:0">.</div>
<div style="margin-top:0; margin-bottom:0">.</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0"> celldm(1)= 22.186293 celldm(2)= 0.000000 celldm(3)= 0.000000<br>
celldm(4)= 0.000000 celldm(5)= 0.000000 celldm(6)= 0.000000<br>
<br>
crystal axes: (cart. coord. in units of alat)<br>
a(1) = ( -0.500000 0.000000 0.500000 )<br>
a(2) = ( 0.000000 0.500000 0.500000 )<br>
a(3) = ( -0.500000 0.500000 0.000000 )<br>
<br>
</div>
<div style="margin-top:0; margin-bottom:0">.</div>
<div style="margin-top:0; margin-bottom:0">.</div>
<div style="margin-top:0; margin-bottom:0">.</div>
<div style="margin-top:0; margin-bottom:0"><br>
</div>
<div style="margin-top:0; margin-bottom:0"> Crystallographic axes<br>
<br>
site n. atom positions (cryst. coord.)<br>
1 Si tau( 1) = ( <span style="background-color:yellow">0.7043430 0.3056728 0.6842995</span> )<br>
2 Si tau( 2) = ( 0.3056728 0.7043430 0.3056847 )<br>
3 Si tau( 3) = ( 0.3056847 0.6842995 0.3056728 )<br>
4 Si tau( 4) = ( 0.6842995 0.3056847 0.7043430 )<br>
5 Si tau( 5) = ( 0.6842995 0.3056728 0.3056847 )<br>
6 Si tau( 6) = ( 0.3056847 0.7043431 0.6842995 )<br>
7 Si tau( 7) = ( 0.3056728 0.6842995 0.7043431 )<br>
8 Si tau( 8) = ( 0.7043431 0.3056847 0.3056728 )<br>
9 Si tau( 9) = ( 0.3056847 0.3056728 0.7043430 )<br>
10 Si tau( 10) = ( 0.6842995 0.7043430 0.3056728 )<br>
11 Si tau( 11) = ( 0.7043430 0.6842995 0.3056847 )<br>
12 Si tau( 12) = ( 0.3056728 0.3056847 0.6842995 )<br>
13 Si tau( 13) = ( 0.2956570 0.6943272 0.3157005 )<br>
14 Si tau( 14) = ( 0.6943272 0.2956570 0.6943153 )<br>
15 Si tau( 15) = ( 0.6943153 0.3157005 0.6943272 )<br>
16 Si tau( 16) = ( 0.3157005 0.6943153 0.2956570 )<br>
17 Si tau( 17) = ( 0.3157005 0.6943272 0.6943153 )<br>
18 Si tau( 18) = ( 0.6943153 0.2956569 0.3157005 )<br>
19 Si tau( 19) = ( 0.6943272 0.3157005 0.2956569 )<br>
20 Si tau( 20) = ( 0.2956569 0.6943153 0.6943272 )<br>
21 Si tau( 21) = ( 0.6943153 0.6943272 0.2956570 )<br>
22 Si tau( 22) = ( 0.3157005 0.2956570 0.6943272 )<br>
23 Si tau( 23) = ( 0.2956570 0.3157005 0.6943153 )<br>
24 Si tau( 24) = ( 0.6943272 0.6943153 0.3157005 )</div>
</span>
<p><br>
</p>
<p><br>
</p>
<div id="m_304204831956264345Signature">
<div name="divtagdefaultwrapper"><font size="3" color="black"><span dir="ltr" style="font-size:12pt; background-color:white"><font size="1"><span style="font-size:13.32px">F</span></font></span></font><font size="3" color="black"><span dir="ltr" style="font-size:12pt; background-color:white"><font size="1"><span style="font-size:13.32px">élix
Musil </span></font><br>
<font size="1"><span style="font-size:13.32px">Doctoral Assistant - Ph.D Student</span></font><br>
<br>
<font size="1"><span style="font-size:13.32px">EPFL STI IMX COSMO</span></font><br>
<font size="1"><span style="font-size:13.32px">LABORATORY OF COMPUTATIONAL SCIENCE AND MODELLING</span></font><br>
<font size="1"><span style="font-size:13.32px">Institute of Materials Science and Engineering</span></font><br>
<font size="1"><span style="font-size:13.32px">MXG 319</span></font><br>
<font size="1"><span style="font-size:13.32px">Station 12</span></font><br>
<font size="1"><span style="font-size:13.32px">CH-1015 Lausanne</span></font><br>
<font size="1"><span style="font-size:13.32px">Switzerland</span></font><br>
<br>
<font size="1"><span style="font-size:13.32px">E-mail: <a href="mailto:felix.musil@epfl.ch" target="_blank">
felix.musil@epfl.ch</a></span></font><br>
<font size="1"><span style="font-size:13.32px"><a href="http://cosmo.epfl.ch/" target="_blank">http://cosmo.epfl.ch/</a></span></font></span></font></div>
</div>
</div>
<br>
______________________________<wbr>_________________<br>
Pw_forum mailing list<br>
<a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>
<a href="http://pwscf.org/mailman/listinfo/pw_forum" rel="noreferrer" target="_blank">http://pwscf.org/mailman/<wbr>listinfo/pw_forum</a><br>
</blockquote>
</div>
<br>
<br clear="all">
<br>
-- <br>
<div 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 208, 33100 Udine, Italy<br>
Phone +39-0432-558216, fax +39-0432-558222<br>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>