Dear <span class="Apple-style-span" style="border-collapse: collapse; font-family: arial, sans-serif; font-size: 13px; ">Eric:</span><div><font class="Apple-style-span" face="arial, sans-serif"><span class="Apple-style-span" style="border-collapse: collapse;">The occupied and unoccupied bands touch each other only at M point(or K point, I forget it).</span></font></div>
<div><font class="Apple-style-span" face="arial, sans-serif"><span class="Apple-style-span" style="border-collapse: collapse;">You must include this point in you k-mesh.</span></font></div><div><font class="Apple-style-span" face="arial, sans-serif"><span class="Apple-style-span" style="border-collapse: collapse;">Furthermore, if you include spin-orbital coupling, the band gap will be opened at this point.<br>
</span></font><br><div class="gmail_quote">On Thu, Mar 10, 2011 at 1:30 AM, Eric Germaneau <span dir="ltr"><<a href="mailto:germaneau@gucas.ac.cn">germaneau@gucas.ac.cn</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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Dear all,<br>
<br>
I'm trying to compute graphene's band gap but get stuck.<br>
From my understanding a scf calculation should provide the same
energy for the highest occupied and lowest occupied level which
means a zero gap.<br>
I played with the number a kpoints a finally got a band gap of 0.57
which is not null.<br>
The scf convergence looks good.<br>
I'm not (yet) an expert in DFT calculation so may did something
wrong or misunderstood something here.<br>
So, I wonder if someone has already successfully performed such
calculation.<br>
I have attached my input file.<br>
Thanks in advance,<br>
<br>
Eric.<br>
<br>
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<a href="mailto:germaneau@gucas.ac.cn" target="_blank">Dr. Éric Germaneau</a><br>
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College of Physical Sciences<br>
Graduate University of Chinese Academy of Sciences<br>
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Beijing 100049<br>
China<br>
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