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Dear Mehmet,<br>
<br>
graphene has zero gap, hence you probably need to include smearing
of the occupations in the scf calculations. <br>
<br>
<br>
HTH<br>
<br>
GS<br>
<br>
On 09/29/2010 04:54 PM, Mehmet Topsakal wrote:
<blockquote
cite="mid:AANLkTi=UgEjkc_u4x250eub4EhACH0TC7FgooKgHNWpq@mail.gmail.com"
type="cite">Dear all,
<div><br>
</div>
<div>For graphene structure, I noticed that I get completely wrong
phonon frequencies when I use KPOINTS such as 9 9 1, 12 12 1, 15 15 1</div>
<div><br>
</div>
<div>For example:<br clear="all">
<br>
</div>
<div>
<div>K_POINTS {automatic}</div>
<div>11 11 1 0 0 0 </div>
<div><br>
</div>
<div>gives realistic frequencies as in 11.phonon.out file </div>
<div><br>
</div>
<div>BUT</div>
<div><br>
</div>
<div>
<div>K_POINTS {automatic}</div>
<div>12 12 1 0 0 0 </div>
</div>
<div><br>
</div>
<div>gives "omega( 1) = -149.592762 [THz] = -4989.910586 [cm-1]"
as in 12.phonon.out</div>
<div><br>
</div>
<div><br>
</div>
<div>What should be the reason ????</div>
<div><br>
</div>
<div>Thanks.</div>
<div><br>
</div>
-- <br>
<br>
Mehmet Topsakal (Ph.D. Student)<br>
UNAM-Institute of Materials Science and Nanotechnology. <br>
Bilkent University. 06800 Bilkent, Ankara/Türkiye<br>
Tel: 0090 312 290 3527 ; Fax: 0090 312 266 4365<br>
UNAM-web : <a moz-do-not-send="true" href="http://www.nano.org.tr"
target="_blank">www.nano.org.tr</a><br>
<br>
</div>
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<br>
<br>
<pre class="moz-signature" cols="72">--
Gabriele Sclauzero, EPFL SB ITP CSEA
PH H2 462, Station 3, CH-1015 Lausanne
</pre>
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