<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<p>Dear Mengxi Wu</p>
<p>If I clearly understand you, you are considering the GAMMA point
where the bands are degenerate. <br>
</p>
<p>At the GAMMA point these bands have the same symmetry to my point
of view, explaining why the dipole matrix is non-zero. Thus your
result is expected to my point of view. <br>
</p>
<p>Best Regards</p>
<p>Xavier<br>
</p>
<br>
<div class="moz-cite-prefix">Le 13/11/2016 à 17:29, Little Grass a
écrit :<br>
</div>
<blockquote
cite="mid:CABMJZxKGtSfRuHL-ZeN_TjGVH7hLS0ZAOnzA4gXuGD6vT+vz2A@mail.gmail.com"
type="cite">
<div dir="ltr"><span style="font-size:12.8px">Dear WIEN2k users,</span>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">I'm trying to study the dipole
matrix elements of MgO at Gamma point, but the dipole matrix
elements between the degenerated bands seem to have been mixed
together. Are there any ways to sort out the degeneracy, so
that the dipole matrix elements are non-zero only for bands
with the same symmetry?</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">The band structure can be
generated from the spaghetti program. In addition, bands with
different symmetries are colored differently with irrep. For
example, Fig1 shows the band structure from X to Gamma to X.
According to symmetry, only the bands with the same color will
be dipole allowed in px. So we expect that the dipole matrix
elements (in file mommat2) for px is zero between bands with
different colors. For example, the dipole matrix elements
between band 6 and band 9 is non-zero, but the dipole matrix
elements between band 7 and 9 or 8 and 9 are zero. But if one
looks at the px component of the dipole matrix element from
the optic program, we see that at Gamma point, the dipole
matrix elements between the degenerated bands are mixed
together. For example, dipole matrix elements between band 6
and 9, between 7 and 9, and between 8 and 9 are all non-zero.
In other words, the dipole matrix is much denser than it
should be.</div>
<div style="font-size:12.8px">So is there a way to fix the
dipole matrix so that the dipole matrix become very sparse and
only bands with the same symmetry have non-zero dipole matrix
elements?</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">Fig1:<a moz-do-not-send="true"
href="http://imgur.com/a/c7p0u">http://imgur.com/a/c7p0u</a></div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">Thanks in advance for the help.</div>
<div style="font-size:12.8px">Best,</div>
<div style="font-size:12.8px">Mengxi Wu</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Wien mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a>
<a class="moz-txt-link-freetext" 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 class="moz-txt-link-freetext" 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>
</body>
</html>