<div dir="ltr"><p class=""><span lang="EN-US" style="font-family:'Courier New'">I already optimized <span style="font-family:arial,sans-serif;font-size:13px">the geometry and lattice constants. i get the following value</span> </span></p>
<p class=""><span lang="EN-US" style="font-family:'Courier New'"> Diagonalizing the dynamical matrix<br>
<br>
q = ( 0.000000000 0.000000000
0.000000000 ) <br>
<br>
**************************************************************************<br>
omega( 1) = -18.907308 [THz] = -630.679895 [cm-1]<br>
omega( 2) = -18.907308 [THz] = -630.679895 [cm-1]<br>
omega( 3) = -18.907308 [THz] = -630.679895 [cm-1]<br>
omega( 4) = -13.087809 [THz] = -436.562323 [cm-1]<br>
omega( 5) = -13.087809 [THz] = -436.562323 [cm-1]<br>
omega( 6) = 2.252439 [THz] = 75.133272 [cm-1]<br>
</span></p></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-05-08 11:29 GMT+01:00 Ari P Seitsonen <span dir="ltr"><<a href="mailto:Ari.P.Seitsonen@iki.fi" target="_blank">Ari.P.Seitsonen@iki.fi</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
Dear Halima,<br>
<br>
(This is probably an FAQ) Did you carefully optimise the geometry and lattice constants before calculating the phonons? Are the imaginary frequencies small, maximum three of them and only at Gamma point? This would be "normal".<br>
<br>
Greetings from Zurich,<br>
<br>
apsi<br>
<br>
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=<u></u>*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=<u></u>-=*=-=*=-=*=-=*=-<br>
Ari Paavo Seitsonen / <a href="mailto:Ari.P.Seitsonen@iki.fi" target="_blank">Ari.P.Seitsonen@iki.fi</a> / <a href="http://www.iki.fi/~apsi/" target="_blank">http://www.iki.fi/~apsi/</a><br>
Institut für Chemie der Universität Zürich, CH-8057 Zürich<br>
Tel: +41 44 63 54 497 / Mobile: +41 79 71 90 935<div class=""><br>
<br>
<br>
On Thu, 8 May 2014, Halima Zaari wrote:<br>
<br>
</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="">
Dear Espresso users<br>
I have performed a phonon calculation of an oxides on 2x2x2 q grid. I am<br>
using pw.x , ph.x; q2r.x, matdyn.x and lambda.x to calculate the <br>
phonon-electron coupling <br>
. However I am getting" NAN" in the file lambda.dat and negative frequencies<br>
in the electron-phonon.out <br>
i can't explain why i get negatives frequencies<br>
Kindly suggest me the possible ways where I can solve this.<br>
cordially<br>
<br>
--<br></div>
H.ZAARIPhD Student in laboratory of magnetism and physics of high energy<div class=""><br>
Faculty of Sciences in Rabat - Morocco<br>
Email: <a href="mailto:halimazaari@gmail.com" target="_blank">halimazaari@gmail.com</a><br>
<br>
<br>
</div></blockquote>
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<font face="georgia, serif">PhD Student in </font><span style="font-family:georgia,serif">laboratory of magnetism and physics of high energy</span></div>
<div><font face="georgia, serif">Faculty of Sciences in Rabat - Morocco</font></div>
<div><font face="georgia, serif">Email:<u> halimazaari<font color="#3366ff"><a href="mailto:boujnah.mourad@gmail.com" target="_blank">@gmail.com</a><br></font></u></font><br></div></font></div>
</div>