<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt">Sir sorry for inconvenience again. I found small small software utility TANGENT.opk for ORIGIN which can draw tangent a point and gives corresponding slope. I am just confused at which point I should take the tangent. What point in data set of imaginary part of epsilon represents ''EDGE''. In other words which point represent ''EDGE''. Kindly guide how to take tangent properly in Origin along Edge. <br><div><br></div><div>Best wishes<br>Masood<br><br> <blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; margin-top: 5px; padding-left: 5px;"> <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> Tuesday, July 9, 2013 2:52 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [Wien] How to calculate optical absorption edge ?<br> </font> </div> <div class="y_msg_container"><br><div id="yiv6890178038">
<div>
<div class="yiv6890178038moz-cite-prefix">I am also using origin to determine the
absorption edge based on epsilon2. <br>
You must simply draw a tangent line along the edge and then read
the intersection between this line and "Eps2 = 0" axis. <br>
<br>
<br>
<br>
<br>
Le 7/9/2013 8:44 AM, Masood Yousaf a écrit :<br>
</div>
<blockquote type="cite">
<div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:12pt;">I would be
grateful if you guide me how to apply this tangent method to the
data of imaginary part of the dielectric function. can I use
Origin to apply this ?<br>
<br>
<div>Best wishes<br>
Masood<br>
<br>
<blockquote style="border-left:2px solid rgb(16, 16, 255);margin-left:5px;margin-top:5px;padding-left:5px;">
<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 <a rel="nofollow" class="yiv6890178038moz-txt-link-rfc2396E" ymailto="mailto:xavier.rocquefelte@cnrs-imn.fr" target="_blank" href="mailto:xavier.rocquefelte@cnrs-imn.fr"><xavier.rocquefelte@cnrs-imn.fr></a><br>
<b><span style="font-weight:bold;">To:</span></b> A
Mailing list for WIEN2k users
<a rel="nofollow" class="yiv6890178038moz-txt-link-rfc2396E" 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> <br>
<b><span style="font-weight:bold;">Sent:</span></b>
Tuesday, July 9, 2013 2:30 PM<br>
<b><span style="font-weight:bold;">Subject:</span></b>
Re: [Wien] How to calculate optical absorption edge
?<br>
</font> </div>
<div class="yiv6890178038y_msg_container"><br>
<div id="yiv6890178038">
<div>
<div class="yiv6890178038moz-cite-prefix">If you
plot epsilon2 (the imaginary part of the
dielectric function) and use the tangent method,
you can estimate the absorption edge from
WIEN2K.<br>
However, it requires to use a proper functional,
allowing to overcome the inherent problems of
DFT, which is a ground state theory, i.e. LDA+U
for correlated systems or hybrid functional...<br>
<br>
Regards<br>
<br>
Xavier<br>
<br>
Le 7/9/2013 7:00 AM, Masood Yousaf a écrit :<br>
</div>
<blockquote type="cite">
<div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:12pt;">Dear Sir, thanks for
your elaboration. Need some further
explanation to overcome the confusion. Is it
possible to determine accurately absorption
edge from WIEN2k code only i.e., from
case.epsilon ? <br>
<div><br>
</div>
<div>Best wishes<br>
Masood<br>
<br>
<blockquote style="border-left:2px solid rgb(16, 16,
255);margin-left:5px;margin-top:5px;padding-left:5px;">
<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 <a rel="nofollow" class="yiv6890178038moz-txt-link-rfc2396E" ymailto="mailto:xavier.rocquefelte@cnrs-imn.fr" target="_blank" href="mailto:xavier.rocquefelte@cnrs-imn.fr"><xavier.rocquefelte@cnrs-imn.fr></a><br>
<b><span style="font-weight:bold;">To:</span></b>
A Mailing list for WIEN2k users <a rel="nofollow" class="yiv6890178038moz-txt-link-rfc2396E" 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>
<br>
<b><span style="font-weight:bold;">Sent:</span></b>
Tuesday, July 9, 2013 12:40 PM<br>
<b><span style="font-weight:bold;">Subject:</span></b>
Re: [Wien] How to calculate
optical absorption edge ?<br>
</font> </div>
<div class="yiv6890178038y_msg_container"><br>
<div id="yiv6890178038">
<div>
<div class="yiv6890178038moz-cite-prefix">Experimentally
an absorption edge (optical
gap) is estimated using the
tangent method. <br>
Thus you should do the same
with your calculated data to
compare optical gap values,
which differ from a
fundamental band gap. <br>
<br>
Indeed, a fundamental band gap
is the smallest band gap
allowing to excite an electron
in unoccupied states (deduced
from electrical measurements -
thus no transition rules). <br>
In contrast, the optical gap
is related to an excitation
using photons, thus it
respects the dipolar
transitions rules (this gap is
usually larger than the
fundamental band gap). <br>
<br>
Regards<br>
<br>
Xavier<br>
<br>
<br>
Le 7/9/2013 3:07 AM, Masood
Yousaf a écrit :<br>
</div>
<blockquote type="cite">
<div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:12pt;">Dear
wien2k users<br>
<br>
Kindly suggest how to
calculate optical absortion
edge in wien2k ? How it
differs from band gap of
material ? I read that first
critical point in imaginary
part of the dielectric
function represents optical
absorption edge. But how to
ensure that which is the
first critical point. Kindly
guide<br>
<br>
<div>Best wishes<br>
Masood<br>
Universiti Tecknologi
Malaysia<br>
</div>
</div>
<br>
<fieldset class="yiv6890178038mimeAttachmentHeader"></fieldset>
<br>
<pre>_______________________________________________
Wien mailing list
<a rel="nofollow" class="yiv6890178038moz-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" class="yiv6890178038moz-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" class="yiv6890178038moz-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>
</div>
</div>
<br>
_______________________________________________<br>
Wien mailing list<br>
<a rel="nofollow" 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><br>
<a rel="nofollow" target="_blank" href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br>
SEARCH the MAILING-LIST at: <a rel="nofollow" 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><br>
<br>
<br>
</div>
</div>
</div>
</blockquote>
</div>
</div>
<br>
<fieldset class="yiv6890178038mimeAttachmentHeader"></fieldset>
<br>
<pre>_______________________________________________
Wien mailing list
<a rel="nofollow" class="yiv6890178038moz-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" class="yiv6890178038moz-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" class="yiv6890178038moz-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>
</div>
</div>
<br>
_______________________________________________<br>
Wien mailing list<br>
<a rel="nofollow" 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><br>
<a rel="nofollow" target="_blank" href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br>
SEARCH the MAILING-LIST at: <a rel="nofollow" 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><br>
<br>
<br>
</div>
</div>
</div>
</blockquote>
</div>
</div>
<br>
<fieldset class="yiv6890178038mimeAttachmentHeader"></fieldset>
<br>
<pre>_______________________________________________
Wien mailing list
<a rel="nofollow" class="yiv6890178038moz-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" class="yiv6890178038moz-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" class="yiv6890178038moz-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>
</div>
</div><br>_______________________________________________<br>Wien mailing list<br><a ymailto="mailto:Wien@zeus.theochem.tuwien.ac.at" href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br><a href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien" target="_blank">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br>SEARCH the MAILING-LIST at: <a 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><br><br></div> </div> </div> </blockquote> </div></div></body></html>