<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>Il giorno 14/feb/2011, alle ore 14.18, Srijan Kumar Saha ha scritto:</div><br><blockquote type="cite">
<br> > Where is the proof that the final symmetry is different from the initial one? <<br><br> Here goes more direct proof:<br><br> Initial symmetry : 48 Sym.Ops. (with inversion). <br> Final symmetry : 6 Sym.Ops. (no inversion). <br></blockquote><div><br></div><div>Where did you get this information from? Was it printed by the code? I never saw a printout of the "Final symmetry", but maybe I am wrong and the code computes and prints it. Which version of the code are you using?</div><br><blockquote type="cite">
<br> > I think that you should not pay attention to differences of the order of 10^-9, <<br><br>If we compare the final & initial positions given in my previous email, then we can see that<br>the differences are quite large. </blockquote><div><br></div><div>From your previous email it looks to me that the atoms are still in the original arrangement with cubic symmetry. I can guess that the volume of the cell has increased a bit (less than 1%) and so the atomic positions, which are always expressed in terms of the INITIAL celldm(1), will scale accordingly on the final output. The largest deviations I can spot out are below 10^-8.</div><div>Moreover, I don't understand why you want to perform such kind of expensive calculation on a supercell. Have you tried with the fundamental unit cell first?</div><div><br></div><div>GS</div><div><br></div><div><br></div><blockquote type="cite">These differences go away if we use <br>
Wentzcovitch Damped Dynamics, instead of BFGS. However, Damped Dynamics stops <br>without convergence (50 iterations completed, stopping). Since this dynamics converge very <br>slowly, I would like to know whether VC-RELAX with BFGS has the above capability of respecting the <br>
symmetry.<br><br>Thanks & regards,<br>Srijan K.<br>CCMT<br>Indian Institute of Science<br>India 560012 <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></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>
</div>
<br></body></html>