<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p><tt>the order of the entries in the pseudopotential list or in
the atomic position list should not affect the result.</tt></p>
<p><tt>however you are not changing only the order. <br>
</tt></p>
<p><tt>1) you are also swapping the two atoms... this too should not
change anything but is not the same as changing the order only
:)<br>
</tt></p>
<p><tt>2) the first calculation is metallic (with a quite large
gaussian smearing, 0.05 Ry is ~ 0.7 eV) the second uses the
default insulating setting. THIS may have a big impact, for two
reasons: i) the fundamental gap in AlSb, if I remember
correctly, is not very large .. comparable to the smearing width
used; ii) being AlSb a polar material the vibrational properties
have a non analytic component ruled by the macroscopic
dielectric properties (Z*, epsilon_infty) that are disabled in
the phonon calculation of metals (where epsilon_infty diverges).
<br>
</tt></p>
<p><tt>Additionally, in the phonon calculation step you should make
sure you do compute Z* and epsilon and include them in the
subsequent phonon dispersion calculation step. <br>
</tt></p>
<p><tt>HTH</tt></p>
<p><tt>stefano</tt><br>
</p>
<div class="moz-cite-prefix">On 30/12/19 23:07, Sheikh Ziauddin
Ahmed wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAJDtt02ddoO8nqWyH-AzUuAHcHrxKtHEJy2Wcz-jmkNN6ns69Q@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">I am trying to calculate the phonon dispersion of
AlSb. I am getting two different results depending on how I am
introducing the atoms in the SCF calculation. Will the order of
the atom change the symmetry of the zinc blende AlSb?
<div><br>
</div>
<div>In the first case the input deck is: </div>
<div>&system<br>
ibrav=2, nat=2, ntyp=2,<br>
ecutwfc = 50, ecutrho = 500,<br>
occupations='smearing',<br>
smearing='gauss',<br>
degauss=0.05,<br>
celldm(1)=11.5944146,<br>
/<br>
&electrons<br>
conv_thr = 1.0e-12<br>
mixing_beta = 0.7<br>
mixing_mode = 'local-TF'<br>
/<br>
ATOMIC_SPECIES<br>
Al 26.98 al_lda_v1.uspp.F.UPF<br>
Sb 121.76 sb_lda_v1.4.uspp.F.UPF<br>
ATOMIC_POSITIONS (alat)<br>
Al 0.0 0.0 0.0<br>
Sb 0.25 0.25 0.25<br>
K_POINTS automatic<br>
6 6 6 0 0 0<br>
</div>
<div><br clear="all">
<div>In the second case the input deck is: </div>
<div> &system<br>
ibrav=2, nat=2, ntyp=2,<br>
ecutwfc = 50, ecutrho = 500,<br>
!occupations='smearing',<br>
!smearing='gauss',<br>
!degauss=0.05,<br>
celldm(1)=11.5944146,<br>
/<br>
&electrons<br>
conv_thr = 1.0e-12<br>
mixing_beta = 0.7<br>
mixing_mode = 'local-TF'<br>
/<br>
ATOMIC_SPECIES<br>
Sb 121.76 sb_lda_v1.4.uspp.F.UPF<br>
Al 26.98 al_lda_v1.uspp.F.UPF<br>
ATOMIC_POSITIONS (alat)<br>
Sb 0.0 0.0 0.0<br>
Al 0.25 0.25 0.25<br>
K_POINTS automatic<br>
6 6 6 0 0 0<br>
</div>
<div><br>
</div>
<div>Thanks in advance!</div>
-- <br>
<div dir="ltr" class="gmail_signature"
data-smartmail="gmail_signature">
<div dir="ltr">
<div
style="margin-bottom:0px;margin-left:0px;padding-bottom:5px">
<div>
<div dir="ltr"><span>
<div>
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div style="font-size:12.8px"><font
color="#444444"><b>Sheikh Ziauddin
Ahmed </b></font></div>
<div style="font-size:12.8px"><font
color="#444444">PhD Candidate</font></div>
<div style="font-size:12.8px"><font
color="#444444">Charles L. Brown
Department of Electrical and
Computer Engineering</font></div>
<div style="font-size:12.8px"><font
color="#444444">University of
Virginia</font></div>
<div style="font-size:12.8px"><font
color="#444444">Email<font
color="#888888">:</font><a
href="mailto:sza9wz@virginia.edu"
target="_blank"
moz-do-not-send="true">sza9wz<u>@virginia.edu</u></a></font></div>
<div>
<div style="font-size:12.8px"><font
color="#444444">LinkedIn</font><font
color="#000000">: </font><span
style="color:rgb(136,136,136);font-size:12.8px"><a
href="https://www.linkedin.com/in/sheikh-ziauddin-ahmed" target="_blank"
moz-do-not-send="true">https://www.linkedin.com/in/sheikh-ziauddin-ahmed</a></span></div>
</div>
</div>
</div>
</div>
</div>
</div>
</span></div>
</div>
</div>
</div>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
Quantum ESPRESSO is supported by MaX (<a class="moz-txt-link-abbreviated" href="http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso</a>)
users mailing list <a class="moz-txt-link-abbreviated" href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a>
<a class="moz-txt-link-freetext" href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a></pre>
</blockquote>
</body>
</html>