<div dir="auto">I'm not an expert of this specific calculation, but I suspect that the equation breaks down if even a tiny negative frequency is present. This because energy conservation between phonons and electrons would not be enforceable in a meaningful way. Sometimes, if the system has internal degrees of freedom, a very fine relax calculation can remove negative frequencies. Or if they arise from interpolation, changing the sum rule method. <br><br><div data-smartmail="gmail_signature">-- <br>Lorenzo Paulatto<br>Written on a virtual keyboard with real fingers</div></div><div class="gmail_extra"><br><div class="gmail_quote">On 29 Jul 2017 10:15 a.m., "Isaiah Moses" <<a href="mailto:imoses87@gmail.com">imoses87@gmail.com</a>> wrote:<br type="attribution"><blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="quoted-text"><div dir="ltr"><div><div><div><div><div><div><div><div><div>Dr Giovanni,<br></div>Thanks a lot.<br></div>I appreciate your response.<br></div>We observed few values of frequencies to be negative.<br></div>Matdyn1 has few more with others having either the first or the first 2/3 to be negative.<br></div>We set those to be zero, modifying lambda.f90 code.<br><br></div>Could that be the problem?<br><br></div>I've attached the input/output for lambda.x execution. Also matdyn1 and 45.<br><br></div>There are 62-points and 33 irreps.<br></div>I appreciate your time.</div></div><div class="elided-text"><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Jul 28, 2017 at 12:17 PM, Isaiah Moses <span dir="ltr"><<a href="mailto:imoses87@gmail.com" target="_blank">imoses87@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Here is <a href="http://lambda.in" target="_blank">lambda.in</a> and out.<br></div><div class="m_-6421853779044963314HOEnZb"><div class="m_-6421853779044963314h5"><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Jul 28, 2017 at 12:13 PM, Isaiah Moses <span dir="ltr"><<a href="mailto:imoses87@gmail.com" target="_blank">imoses87@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div><div><div><div><div><div><div><div>Dr Giovanni,<br></div>Thanks a lot.<br></div>I appreciate your response.<br></div>We observed few values of frequencies to be negative.<br></div>Matdyn1 has few more with others having either the first or the first 2/3 to be negative.<br></div>We set those to be zero, modifying lambda.f90 code.<br><br></div>Could that be the problem?<br><br></div>I've attached the input/output for lambda.x execution. Also matdyn1 and 45.<br><br></div>There are 62-points and 33 irreps.<br></div>I appreciate your time.<span class="m_-6421853779044963314m_-7575404325376520420HOEnZb"><font color="#888888"><br><br></font></span></div><span class="m_-6421853779044963314m_-7575404325376520420HOEnZb"><font color="#888888">Isaiah<br></font></span></div><div class="m_-6421853779044963314m_-7575404325376520420HOEnZb"><div class="m_-6421853779044963314m_-7575404325376520420h5"><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Jul 28, 2017 at 10:41 AM, Giovanni Cantele <span dir="ltr"><<a href="mailto:giovanni.cantele@spin.cnr.it" target="_blank">giovanni.cantele@spin.cnr.it</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">Not that easy to answer without seeing relevant input/output files.<div><br></div><div>As far as I know, Tc is quite difficult to converge. Did you made VERY VERY VERY careful checks on convergence with</div><div>resect to ALL calculation parameters, starting from phonon frequencies?</div><div><br></div><div>Giovanni</div><div><br></div><div><br><div><blockquote type="cite"><div><div class="m_-6421853779044963314m_-7575404325376520420m_1262743981477134988h5"><div>On 28 Jul 2017, at 11:37, Isaiah Moses <<a href="mailto:imoses87@gmail.com" target="_blank">imoses87@gmail.com</a>> wrote:</div><br class="m_-6421853779044963314m_-7575404325376520420m_1262743981477134988m_-1865112605733877079Apple-interchange-newline"></div></div><div><div><div class="m_-6421853779044963314m_-7575404325376520420m_1262743981477134988h5"><div dir="ltr"><div class="gmail_quote"><span dir="ltr"></span><div dir="ltr"><div><div><div><div><div>Dear everyone,<br><br></div>I did an el-ph calculation of a monoclinic structure and am getting really strange values of Tc . See the result below<br>lambda omega_log T_c<br> 0.00994 112.048 0.10012314E+08 <br> 0.03760 92.373 0.13380511E+10 <br> 0.07564 90.247 0.39802174E+19 <br> 0.09959 89.414 0.19865362E+78 <br> 0.11010 89.463 0.40671597-151 <br> 0.11454 90.329 0.16986711E-65 <br> 0.11678 92.320 0.99512429E-51 <br> 0.11772 94.657 0.29927798E-46 <br> 0.11744 97.141 0.16242032E-47 <br> 0.11619 99.442 0.65514785E-54 <br><br></div>I'm wondering why such values.<br><br></div>Any comment shall be greatly appreciated.<br><br></div>Thanks,<br></div>Isaiah<span class="m_-6421853779044963314m_-7575404325376520420m_1262743981477134988m_-1865112605733877079HOEnZb"><font color="#888888"><br clear="all"><div><div><div><div><div><div><br>-- <br><div class="m_-6421853779044963314m_-7575404325376520420m_1262743981477134988m_-1865112605733877079m_-1206119509869367898gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div><div>Isaiah Abu Moses<br></div><div>Graduate Student,<br></div>Physics Department,<br></div>University of Ibadan,<br></div>Nigeria<br></div></div></div></div></div></div>
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<div style="color:rgb(0,0,0);letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;word-wrap:break-word">-- <br><br>Giovanni Cantele, PhD<br>CNR-SPIN<br>c/o Dipartimento di Fisica<br>Universita' di Napoli "Federico II"<br>Complesso Universitario M. S. Angelo - Ed. 6<br>Via Cintia, I-80126, Napoli, Italy<br>e-mail: <a href="mailto:giovanni.cantele@spin.cnr.it" target="_blank">giovanni.cantele@spin.cnr.it</a><br>Phone: <a href="tel:+39%20081%20676910" value="+39081676910" target="_blank">+39 081 676910</a><br>Skype contact: giocan74<br><br>ResearcherID: <a href="http://www.researcherid.com/rid/A-1951-2009" target="_blank">http://www.researcherid.com/ri<wbr>d/A-1951-2009</a><br>Web page: <a href="http://people.fisica.unina.it/~cantele" target="_blank">http://people.fisica.unina.it/<wbr>~cantele</a><br></div>
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