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A final question about that! Is there a way to check the frequencies of the Irreducible representations once each one is done or one has just to wait for the whole vibrational modes calculations to finish; The reason i am asking this is that since one might get negativefrequencies , I was wondering if I can check that before the whole calculation terminates (which takes 25 days) so I then can see what the problem is and lower the threshold if it is what is going wrong. Are those frequencies written to a file other than the output one?<div><br></div><div>Thanks</div><div><br></div><div>Elie<br><br><div><div id="SkyDrivePlaceholder"></div><hr id="stopSpelling">Date: Mon, 14 May 2012 09:45:53 +0200<br>Subject: Re: [Pw_forum] Irreps and vibrational modes<br>From: lorenzo.paulatto@impmc.upmc.fr<br>To: elie.moujaes@hotmail.co.uk<br><br><br><br><div class="ecxgmail_quote">On Mon, May 14, 2012 at 4:07 AM, Elie M <span dir="ltr"><<a href="mailto:elie.moujaes@hotmail.co.uk">elie.moujaes@hotmail.co.uk</a>></span> wrote:<br><blockquote class="ecxgmail_quote" style="border-left:1px #ccc solid;padding-left:1ex">
<div><div dir="ltr"><div>(1) Are all the modes vibrational?</div></div></div></blockquote><div><br></div><div>No, at Gamma you always have 3 translational modes of zero energy </div><blockquote class="ecxgmail_quote" style="border-left:1px #ccc solid;padding-left:1ex">
<div><div dir="ltr"><div><br></div><div>(2) Are any modes missing from the calculation like optical or accoustical modes?</div></div></div></blockquote><div> </div><div>No </div><blockquote class="ecxgmail_quote" style="border-left:1px #ccc solid;padding-left:1ex">
<div><div dir="ltr"><div><br></div><div>(3) i did the calculation and got two of the modes negative which means either threshold is high or the ecutwav must be at least eight times ecutrho. Is a threshold of 10^(-15) still too high for such a system?</div>
</div></div></blockquote><div><br></div><div>This is FAQ2 for phonon calculations: <a href="http://www.quantum-espresso.org/?page_id=366#7.2" target="_blank">http://www.quantum-espresso.org/?page_id=366#7.2</a></div><div><br></div><div><br>
</div><div><br></div><blockquote class="ecxgmail_quote" style="border-left:1px #ccc solid;padding-left:1ex"><div><div dir="ltr"><div><b><br></b></div><div><b><br></b></div><div>Thanks</div><div><br></div><div>
Elie</div><div>University of Nottingham</div><div>NG7 2RD</div><div>UK</div> </div></div>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div>Lorenzo Paulatto IdR @ IMPMC/CNRS & Université Paris 6</div><div>phone: +33 (0)1 44275 084 / skype: paulatz</div><div>www: <a href="http://www-int.impmc.upmc.fr/~paulatto/" target="_blank">http://www-int.impmc.upmc.fr/~paulatto/</a></div>
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