<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>Il giorno 24/nov/2010, alle ore 10.39, Mahmoud Payami ha scritto:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Dear QE experts,<br>I am doing slab calculations, and have let the interlayer spacings change <br>along z-direction. I sometimes encounter the message: "the symmetry <br>opetarion #... is not...", and sometimes this problem causes the program <br></div></blockquote><div><br></div><div>Do you mean "Warning: symmetry operation #N not allowed"? This is not an error, but simply a warning, please have a look here:</div><div><br></div><div><a href="http://www.quantum-espresso.org/user_guide/node50.html#SECTION0001110200000000000000">http://www.quantum-espresso.org/user_guide/node50.html#SECTION0001110200000000000000</a></div><div><br></div><div>I doubt that this would cause the program to stop.</div><br><blockquote type="cite"><div>stop. However, I followed Eyvaz's suggestion in the forum and added <br>"nosym=.true." in &SYSTEM. Now there is no complain about symmetry operation <br>but the number of k-points has been increased. </div></blockquote><div><br></div><div>Of course, they cannot be reduced by symmetry since you asked the code to ignore any symmetry operation that might be present.</div><br><blockquote type="cite"><div>My question is: using <br>"nosym=.true.", what symmetry operations are ignored, and where should I <br></div></blockquote><div><br></div>All.</div><div><br><blockquote type="cite"><div>refer to find out which symmetry operation number refers to what?<br></div></blockquote><div><br></div>use verbosity = 'high' in namelist &control or look into the source code.</div><div><br></div><div>HTH</div><div><br></div><div>GS</div><div><br><blockquote type="cite"><div>Best regards,<br>Mahmoud Payami,<br><br>Physics Group, AEOI, Tehran, Iran. <br><br><br>_______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>http://www.democritos.it/mailman/listinfo/pw_forum<br></div></blockquote></div><br><div>
<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>
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