<html><head><base href="x-msg://14/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Yes, <div><br></div><div> I perfectly agree with Eyvaz! Moreover the experimental bandgap is underestimated within LDA or GGA, and for 4H-SiC you would get about 2.2-2.3 eV with LDA. </div><div><br></div><div> How do you measure the bandgap? Beware that in the fundamental cell the bandgap is not a direct one, but it might become such when you use a supercell (because of the refolding of the Brillouin zones).</div><div><br></div><div><br></div><div>HTH</div><div><br></div><div>GS</div><div><br><div><div><div>Il giorno 03/apr/2011, alle ore 10.59, Eyvaz Isaev ha scritto:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; ">Hi,<span class="Apple-converted-space"> </span><br><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> <pre><font size="4">>The bandgap of 8-atoms is around 10-12 eV, <br>>but that of 72-atom is around 5-7 eV.<br> <br>This is unbelievable, as SiC is an indirect band gap semiconductor and <br>the bandgap is around (2.5 - 3)eV depending on crystal modification <br></font>(3C-SiC, <i>2H</i>-SiC; <i>4H</i>-SiC; <i>6H</i>-SiC, etc.). <br><span>See <a target="_blank" href="http://www.matprop.ru/SiC_bandstr">http://www.matprop.ru/SiC_bandstr</a></span><br><br>So, check carefully your input/output files.<br><br>Bests,<br>Eyvaz.<br><br></pre></div>-------------------------------------------------------------------<br>Prof. Eyvaz Isaev,<span class="Apple-converted-space"> </span><br>Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden<span class="Apple-converted-space"> </span><br>Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia,<span class="Apple-converted-space"> </span><br><a href="mailto:isaev@ifm.liu.se">isaev@ifm.liu.se</a>,<span class="Apple-converted-space"> </span><a href="mailto:eyvaz_isaev@yahoo.com">eyvaz_isaev@yahoo.com</a><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><br><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold; ">From:</span></b><span class="Apple-converted-space"> </span>pari shok <<a href="mailto:parishok@gmail.com">parishok@gmail.com</a>><br><b><span style="font-weight: bold; ">To:</span></b><span class="Apple-converted-space"> </span><a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a><br><b><span style="font-weight: bold; ">Sent:</span></b><span class="Apple-converted-space"> </span>Sun, April 3, 2011 1:34:51 AM<br><b><span style="font-weight: bold; ">Subject:</span></b><span class="Apple-converted-space"> </span>[Pw_forum] shift of energy<br></font><br><pre><font size="4">Dear Paolo,<br>DOS of 72-atom SiC shows a shift of energy with respect to 8-atom SiC.The bandgap of 8-atoms is around 10-12 eV, but that of 72-atom is around 5-7 eV.<br>Would you please help me to understand this shift.<br>
Thanks again.<br>P Shok<br>UMD<br>On Apr 1, 2011, at 21:36 , pari shok wrote:<br><br>><i> The DOS of 72-atom SiC (supercell) shows a shift of energy.<br></i><br>a shift with respect to what?<br>---<br>Paolo Giannozzi, Dept of Chemistry&Physics&Environment,<br>
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>Phone +39-0432-558216, fax +39-0432-558222</font><br></pre></div></div></div><br>_______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br><a href="http://www.democritos.it/mailman/listinfo/pw_forum">http://www.democritos.it/mailman/listinfo/pw_forum</a><br></div></span></blockquote></div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div><span class="Apple-style-span" style="color: rgb(126, 126, 126); font-size: 16px; font-style: italic; "><br class="Apple-interchange-newline">§ Gabriele Sclauzero, EPFL SB ITP CSEA</span></div><div><font class="Apple-style-span" color="#7E7E7E"><i> PH H2 462, Station 3, CH-1015 Lausanne</i></font></div></span>
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