<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <meta content="text/html; charset=windows-1252"
      http-equiv="Content-Type">
    <title></title>
  </head>
  <body bgcolor="#ccccff" text="#000000">
    Dear Mehmet and Hui Wang,<br>
    <br>
    That's what I did.<br>
    From my calculations the occupied and unoccupied bands touch only at
    K point.<br>
    I was just confused because the scf calculation does not output a
    zero gap.<br>
    I mean the line "highest occupied, lowest unoccupied level" shows
    two different values and I expected them to be equal.<br>
    So, it seems I did not too bad in fact. <br>
    But how to experimentally get a zero gap then?<br>
    Thanks,<br>
    <br>
                        Eric.<br>
    <br>
    On 03/09/2011 07:02 AM, Mehmet Topsakal wrote:
    <blockquote
      cite="mid:AANLkTik18472oYR_2Fqxd7NUv50Krez=F-RQKSWpYLEe@mail.gmail.com"
      type="cite">
      <meta charset="utf-8">
      Dear <span style="border-collapse: collapse; font-family:
        arial,sans-serif; font-size: 13px;">Eric,</span>
      <div><br>
      </div>
      <div><span style="border-collapse: collapse; font-family:
          arial,sans-serif; font-size: 13px;"></span>In addition, if you
        select 18x18x1 kpoints, your mesh should include both K and M
        points.</div>
      <div><br>
      </div>
      <div>But for a band-structure calculation, you should arrange a
        kpoints list along special directions, such as from
        GAMMA-to-M-to-K-to-GAMMA, and do a nscf calculation....</div>
      <div><br>
      </div>
      <div><br>
        <div> <br>
          <div class="gmail_quote">On Wed, Mar 9, 2011 at 11:28 AM,
            xirainbow <span dir="ltr"><<a moz-do-not-send="true"
                href="mailto:nkxirainbow@gmail.com">nkxirainbow@gmail.com</a>></span>
            wrote:<br>
            <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
              0.8ex; border-left: 1px solid rgb(204, 204, 204);
              padding-left: 1ex;"> Dear <span style="border-collapse:
                collapse; font-family: arial,sans-serif; font-size:
                13px;">Eric:</span>
              <div><font face="arial, sans-serif"><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 face="arial, sans-serif"><span
                    style="border-collapse: collapse;">You must include
                    this point in you k-mesh.</span></font></div>
              <div><font face="arial, sans-serif"><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">
                  <div>
                    <div class="h5">On Thu, Mar 10, 2011 at 1:30 AM,
                      Eric Germaneau <span dir="ltr"><<a
                          moz-do-not-send="true"
                          href="mailto:germaneau@gucas.ac.cn"
                          target="_blank">germaneau@gucas.ac.cn</a>></span>
                      wrote:<br>
                    </div>
                  </div>
                  <blockquote class="gmail_quote" style="margin: 0pt 0pt
                    0pt 0.8ex; border-left: 1px solid rgb(204, 204,
                    204); padding-left: 1ex;">
                    <div>
                      <div class="h5">
                        <div bgcolor="#ccccff" text="#000000"> 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>
                          <div>-- <br>
                            <center> <font color="#946e8c"> <em> Be
                                  the change you wish to see in the
                                  world<br>
                                </em> <small> <font color="#946e8c"> —
                                    Mahatma Gandhi —<br>
                                  </font></small> <br>
                                <a moz-do-not-send="true"
                                  href="mailto:germaneau@gucas.ac.cn"
                                  target="_blank">Dr. Éric Germaneau</a><br>
                                <br>
                                College of Physical Sciences<br>
                                Graduate University of Chinese Academy
                                of Sciences<br>
                                Yuquan Road 19A<br>
                                Beijing 100049<br>
                                China<br>
                                <br>
                                <small> <em> <font style="color:
                                      rgb(73, 136, 72);" face="Times">
                                      Please consider the environment
                                      before printing this email.<br>
                                      Considérez svp l'environnement
                                      avant d'imprimer cet email. </font>
                                  </em> </small> </font></center>
                          </div>
                        </div>
                        <br>
                      </div>
                    </div>
                    _______________________________________________<br>
                    Pw_forum mailing list<br>
                    <a moz-do-not-send="true"
                      href="mailto:Pw_forum@pwscf.org" target="_blank">Pw_forum@pwscf.org</a><br>
                    <a moz-do-not-send="true"
                      href="http://www.democritos.it/mailman/listinfo/pw_forum"
                      target="_blank">http://www.democritos.it/mailman/listinfo/pw_forum</a><br>
                    <br>
                  </blockquote>
                </div>
                <br>
                <br clear="all">
                <br>
                -- <br>
                ____________________________________<br>
                Hui Wang<br>
                School of physics, Fudan University, Shanghai, China<br>
              </div>
              <br>
              _______________________________________________<br>
              Pw_forum mailing list<br>
              <a moz-do-not-send="true" href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>
              <a moz-do-not-send="true"
                href="http://www.democritos.it/mailman/listinfo/pw_forum"
                target="_blank">http://www.democritos.it/mailman/listinfo/pw_forum</a><br>
              <br>
            </blockquote>
          </div>
          <br>
          <br clear="all">
          <br>
          -- <br>
          <br>
          Mehmet Topsakal  (Ph.D. Student)<br>
          UNAM-Institute of Materials Science and Nanotechnology.<br>
          Bilkent University. 06800 Bilkent, Ankara/Turkey<br>
          Tel: 0090 312 290 3527 ; Fax: 0090 312 266 4365<br>
          <a moz-do-not-send="true"
            href="http://www.researcherid.com/rid/A-5015-2010"
            target="_blank">http://www.researcherid.com/rid/A-5015-2010</a><br>
          <br>
        </div>
      </div>
      <pre wrap=""><fieldset class="mimeAttachmentHeader"></fieldset>
_______________________________________________
Pw_forum mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a>
<a class="moz-txt-link-freetext" href="http://www.democritos.it/mailman/listinfo/pw_forum">http://www.democritos.it/mailman/listinfo/pw_forum</a>
</pre>
    </blockquote>
    <br>
    <div class="moz-signature">-- <br>
      <center> <font color="#946e8c"> <em> Be the change you wish to
            see in the world<br>
          </em> <small> <font color="#946e8c"> — Mahatma Gandhi —<br>
            </font></small> <br>
          <a href="mailto:germaneau@gucas.ac.cn">Dr. Éric Germaneau</a><br>
          <br>
          College of Physical Sciences<br>
          Graduate University of Chinese Academy of Sciences<br>
          Yuquan Road 19A<br>
          Beijing 100049<br>
          China<br>
          <br>
          <small> <em> <font style="color: rgb(73, 136, 72);"
                face="Times"> Please consider the environment before
                printing this email.<br>
                Considérez svp l'environnement avant d'imprimer cet
                email. </font> </em> </small> </font></center>
    </div>
  </body>
</html>