<div>Thank you for your answer Stefano,</div>  <div>Of course this explains the different frequencies,</div>  <div>and that also means that I misunderstand the kpoints given in example 5,</div>  <div>about band structure for an fcc,</div>  <div>and Dr. Marzari's explanation to another QE user,</div>  <div>who was confused like me.</div>  <div><A href="http://www.democritos.it/pipermail/pw_forum/2006-June/004365.html">http://www.democritos.it/pipermail/pw_forum/2006-June/004365.html</A></div>  <div> </div>  <div>Thank you again,</div>  <div>Emine Kucukbenli<BR><BR><B><I>Stefano Baroni <baroni@sissa.it></I></B> wrote:</div>  <BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">Emine: (001) and (011) are *NOT* two "X" points in the FCC Brillouin zone. The difference between the second and the first (010) is *NOT* a reciprocal-space vector. If it was, X would also be, which you will agree it is not. As a matter of fact,
 (011) has its own nickname (it is called "K"). No surprise, therefore, that frequencies @K are different from frequencies @X. Are these arguments clear and convincing enough? Stefano  <DIV><BR class=khtml-block-placeholder>  <DIV><BR>  <DIV>  <DIV>On Dec 9, 2006, at 11:10 PM, e kb wrote:</DIV><BR class=Apple-interchange-newline>  <BLOCKQUOTE type="cite">  <DIV>Dear QE users,</DIV>  <DIV>I am performing phonon calculations for a zinc blende structure,</DIV>  <DIV>I calculated the frequencies at high symmetry points, evaluating a single point at each time.</DIV>  <DIV>So I followed the procedure of scf, nscf and ph.x calculation one by one for L(0.5 0.5 0.5) - Gamma - X(0,0,1) - X(0,1,1) points.</DIV>  <DIV>In these calculations every parameter (else than q-vector in &phonon list in nscf calculation and phonon card for ph.x input of course) is kept fixed. </DIV>  <DIV> </DIV>  <DIV>Although I expect the frequencies at two X points - (0,0,1) and
 (0,1,1) - to be the same,</DIV>  <DIV>the difference in TA modes' frequencies are around 30 cm-1, </DIV>  <DIV>in the other ones, around  5 cm-1.</DIV>  <DIV> </DIV>  <DIV>I would like to attribute this to unconverged lattice parameters, cut off energies or thresholds etc. but what I do not understand is why the program treats these two points differently, although they should be equivalent. So I expect to see the same value for frequency at these points, even if it is wrong, highly negative, or sth else that it should not be.</DIV>  <DIV> </DIV>  <DIV>I will appreciate any answers.</DIV>  <DIV>Thank you.</DIV>  <DIV> </DIV>  <DIV>Emine Kucukbenli</DIV>  <DIV> </DIV>  <DIV> </DIV>  <DIV><BR class=khtml-block-placeholder></DIV>  <HR SIZE=1>  Everyone is raving about <A href="http://us.rd.yahoo.com/evt=42297/*http://advision.webevents.yahoo.com/mailbeta">the all-new Yahoo! Mail beta.</A></BLOCKQUOTE></DIV><BR>  <DIV><SPAN
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 style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px">Please, if possible, don't</SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></FONT><FONT class=Apple-style-span size=3><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px">  </SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></FONT><FONT class=Apple-style-span size=3><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span
 style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px">send me MS Word or PowerPoint attachments</SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></FONT></DIV>  <DIV style="MARGIN: 0px"><FONT class=Apple-style-span size=3><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span
 style="FONT-SIZE: 12px">Why? See:</SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></FONT><FONT class=Apple-style-span size=3><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px"><SPAN class=Apple-style-span style="FONT-SIZE: 12px">  </SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></FONT><A href="http://www.gnu.org/philosophy/no-word-attachments.html"><FONT class=Apple-style-span color=#0023e9 size=3><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR: rgb(0,35,233); khtml-text-decorations-in-effect: underline"><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR:
 rgb(0,35,233); khtml-text-decorations-in-effect: underline"><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR: rgb(0,35,233); khtml-text-decorations-in-effect: underline"><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR: rgb(0,35,233); khtml-text-decorations-in-effect: underline"><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR: rgb(0,35,233); khtml-text-decorations-in-effect: underline"><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR: rgb(0,35,233); khtml-text-decorations-in-effect: underline"><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR: rgb(0,35,233); khtml-text-decorations-in-effect: underline"><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR: rgb(0,35,233); khtml-text-decorations-in-effect: underline"><SPAN class=Apple-style-span style="FONT-SIZE: 12px; COLOR: rgb(0,35,233); khtml-text-decorations-in-effect:
 underline">http://www.gnu.org/philosophy/no-word-attachments.html</SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></FONT></A></DIV>  <DIV><BR class=khtml-block-placeholder></DIV><BR class=Apple-interchange-newline></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></DIV><BR></DIV></DIV></BLOCKQUOTE><BR><p>

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