<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt">Dear Xavier<br><br>thank you very much for your reply. <br>Actually, I have repeated the calculations again. I see the spectra are almost <br>same for 2000 and 3000 kpoints but still there is a significant change in the spectra for 90000 kpoints.<br>how can I explain it? furthermore, when you said 2000, 3000 kpoints, your means is in the<br> BZ or IBZ?<br>Best Regards<br>Ali<br><div><span><br></span></div><div><br></div> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div dir="ltr"> <hr size="1"> <font face="Arial" size="2"> <b><span style="font-weight:bold;">From:</span></b> Rocquefelte <xavier.rocquefelte@cnrs-imn.fr><br> <b><span style="font-weight: bold;">To:</span></b> A Mailing list for
WIEN2k users <wien@zeus.theochem.tuwien.ac.at> <br> <b><span style="font-weight: bold;">Sent:</span></b> Monday, September 30, 2013 6:43 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [Wien] optic sum rules<br> </font> </div> <div class="y_msg_container"><br><div id="yiv4501395949"><div>
<div class="yiv4501395949moz-cite-prefix">There is definitely no need to go to
such a high number of k-points. <br clear="none">
In the paper of Claudia, they were looking at metallic compounds,
for which we need to have a very dense k-mesh (for the intraband
transitions). <br clear="none">
In your case you expect a semiconductor and thus you will have
only interband transitions. Thus 6000 kpoints is already converged
to my point of view. <br clear="none">
I should say that the best way to insure the convergency in the
present case is to plot the epsilon2 as a function of the energy
for instance and to compare this quantity with different k-meshes.
In your case, try to do 300 kpoints first and then 500, 1000,
2000, 3000 kpoints ... You will certainly reach the convergency at
about 1000-2000 kpoints ...<br clear="none">
<br clear="none">
Regards<br clear="none">
<br clear="none">
Xavier<br clear="none">
P.S.: The values obtained for 90000 kpoints are curious but I
imagine that you had a prob<br clear="none">
<br clear="none">
<br clear="none">
Le 9/30/2013 4:59 PM, ali ghafari a écrit :<br clear="none">
</div>
<blockquote type="cite">
<div class="yiv4501395949yqt8712700312" id="yiv4501395949yqt54255"><div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:12pt;">
<div class="yiv4501395949msg-body yiv4501395949inner yiv4501395949undoreset" style="">
<div id="yiv4501395949">
<div>
<div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:12pt;">
<div id="yiv4501395949">
<div>
<div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:12pt;">
<div>Dear Prof. Blaha</div>
<div><br clear="none">
</div>
<div style="color:rgb(0, 0, 0);font-size:16px;font-family:times new roman, new york, times, serif;background-color:transparent;font-style:normal;">I
have calculated the optical properties of TiSe2
by MBJ potential with 6000, 50000 and 90000
kpoints which generated after scf by x kgen as
discussed in the UG.<br clear="none">
As discussed in the paper of Prof. Claudia Draxl
(computer physics comm. 175, 1-14 (2006)) the
sum rule 1 and 2 show 'an effective number of
electrons contributing to the absoption process
as a function of energy'.<br clear="none">
but my calculations lead to :<br clear="none">
6000 kpoints: <br clear="none">
<pre>sum rule 1: Int(sigma)dw 19.14
sum rule 2: Int(eloss.w)dw 18.93
sum rule 3: Int(eloss/w)dw 1.51
</pre>
50000 kpoints<br clear="none">
<pre>sum rule 1: Int(sigma)dw 19.08
sum rule 2: Int(eloss.w)dw 18.94
sum rule 3: Int(eloss/w)dw 1.52</pre>
<pre>
90000 kpoints
sum rule 1: Int(sigma)dw 10.125
sum rule 2: Int(eloss.w)dw 10.035
sum rule 3: Int(eloss/w)dw 1.51
</pre>
the results show that in 90000 kpoints the value
of 'sum rule 2' significantly decreases . in the
UG it has mensioned that for the optic we need
dense kpoints but how many? how can I check it
for optic? <br clear="none">
Best Regards <br clear="none">
</div>
<div style="color:rgb(0, 0, 0);font-size:16px;font-family:times new roman, new york, times, serif;background-color:transparent;font-style:normal;">Ali</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div></div>
<br clear="none">
<fieldset class="yiv4501395949mimeAttachmentHeader"></fieldset>
<br clear="none">
<pre>_______________________________________________
Wien mailing list
<a rel="nofollow" shape="rect" class="yiv4501395949moz-txt-link-abbreviated" ymailto="mailto:Wien@zeus.theochem.tuwien.ac.at" target="_blank" href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a>
<a rel="nofollow" shape="rect" class="yiv4501395949moz-txt-link-freetext" target="_blank" href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a>
SEARCH the MAILING-LIST at: <a rel="nofollow" shape="rect" class="yiv4501395949moz-txt-link-freetext" target="_blank" href="http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html">http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html</a>
</pre>
</blockquote>
<br clear="none">
</div></div><br><div class="yqt8712700312" id="yqt63573">_______________________________________________<br clear="none">Wien mailing list<br clear="none"><a shape="rect" ymailto="mailto:Wien@zeus.theochem.tuwien.ac.at" href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br clear="none"><a shape="rect" href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien" target="_blank">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br clear="none">SEARCH the MAILING-LIST at: <a shape="rect" href="http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html" target="_blank">http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html</a><br clear="none"></div><br><br></div> </div> </div> </div></body></html>