<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
<title></title>
</head>
<body bgcolor="#ffffff" text="#000000">
Dear Peter,<br>
Thank you very much<br>
Pablo de la Mora<br>
<br>
Peter Blaha wrote:
<blockquote
cite="midPine.LNX.4.58.0511091023330.10129@susi.theochem.tuwien.ac.at"
type="cite">
<pre wrap="">Of course, the Kohn-Sham eigenvalues are not supposed to be the experimental
measured excitation energies. Nevertheless, many people use them as such.
Experience (and some theoretical considerations as the "discontinuity problem")
has shown, that for insulators/semiconductors the gap comes out about 50 % too
small (and for very small gap semiconductors it may vanish at all); while
for metals the bands (in particular around EF) are pretty good (though not
perfect) in many cases (fermi surfaces, angle resolved photoemission).
Thus I'd expect that for MgB2 the bands agree quite well with PES or FS
measurements.
I would NOT use the Engel-Vosko GGA (option 25) for metals !
</pre>
<blockquote type="cite">
<pre wrap="">Dear WIEN users,
If the gaps are not correct with the three options in the program; then in
the case of several bands the bandedges should not be very precise. Is that
correct?
For example, in MgB2 there are four bands at Ef, but two of them have the
upper edge at ~0.8eV is this value correct?
Is the GGA option 25 stil available and would it give the correct values
for these cases?
Yours
Pablo de la Mora
-------------------------------------------
Peter Blaha wrote:
</pre>
<blockquote type="cite">
<pre wrap="">====
Peter Blaha <a class="moz-txt-link-rfc2396E" href="mailto:pblaha@theochem.tuwien.ac.at"><pblaha@theochem.tuwien.ac.at></a>
submitted the following contribution:
====
</pre>
<blockquote type="cite">
<pre wrap="">I make calculations of AlN,GaN and InN in wurtzite structure using
WIEN97.10
The bandgaps for AlN y GaN are 50% below of the experimental value, but
the bandgap for InN is zero.
</pre>
</blockquote>
<pre wrap="">This is what LDA or the common GGAs give.
</pre>
<blockquote type="cite">
<pre wrap="">How I can make calculations more precise of bandgaps in WIEN97.10?
</pre>
</blockquote>
<pre wrap="">You can use GGA option 25. This is due to Engel and Vosko. It gives much
better bandgaps (often even pretty good), but you have to pay a price:
Never use the total energy! Equillibrium volumes,... are way too large.
</pre>
</blockquote>
<pre wrap="">
</pre>
</blockquote>
<pre wrap=""><!---->
P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671 FAX: +43-1-58801-15698
Email: <a class="moz-txt-link-abbreviated" href="mailto:blaha@theochem.tuwien.ac.at">blaha@theochem.tuwien.ac.at</a> WWW: <a class="moz-txt-link-freetext" href="http://info.tuwien.ac.at/theochem/">http://info.tuwien.ac.at/theochem/</a>
--------------------------------------------------------------------------
_______________________________________________
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>
</pre>
</blockquote>
<br>
</body>
</html>