<div dir="ltr"><div><div><div><div>Dear Zhishuo,<br><br></div>You can see the mode information when verbosity is high in scf output (report) file. I am sorry, if the pictures are not visible. Here is a result with a certain pseudo operating on ibrav 4 crystal structure:<br> q = ( 0.000000000 0.000000000 0.000000000 ) <br><br> **************************************************************************<br> freq ( 1) = -0.917705 [THz] = -30.611333 [cm-1]<br> freq ( 2) = 0.892747 [THz] = 29.778839 [cm-1]<br> freq ( 3) = 0.892747 [THz] = 29.778839 [cm-1]<br> freq ( 4) = 5.229748 [THz] = 174.445607 [cm-1]<br> freq ( 5) = 5.229748 [THz] = 174.445607 [cm-1]<br> freq ( 6) = 7.453800 [THz] = 248.632002 [cm-1]<br> freq ( 7) = 7.453800 [THz] = 248.632002 [cm-1]<br> freq ( 8) = 7.469963 [THz] = 249.171131 [cm-1]<br> freq ( 9) = 9.218972 [THz] = 307.511813 [cm-1]<br> **************************************************************************<br><br> Mode symmetry, D_3h (-62m) point group:<br><br> freq ( 1 - 1) = -30.6 [cm-1] --> A''2 I <br> freq ( 2 - 3) = 29.8 [cm-1] --> E' I+R<br> freq ( 4 - 5) = 174.4 [cm-1] --> E'' R <br> freq ( 6 - 7) = 248.6 [cm-1] --> E' I+R<br> freq ( 8 - 8) = 249.2 [cm-1] --> A'_1 R <br> freq ( 9 - 9) = 307.5 [cm-1] --> A''2 I <br><br><br></div>And here is the result done on the same structure with another pseudo with same constraint on same structure:<br> q = ( 0.000000000 0.000000000 0.000000000 ) <br><br> **************************************************************************<br> freq ( 1) = 0.215200 [THz] = 7.178313 [cm-1]<br> freq ( 2) = 0.254327 [THz] = 8.483433 [cm-1]<br> freq ( 3) = 0.510191 [THz] = 17.018144 [cm-1]<br> freq ( 4) = 5.050369 [THz] = 168.462168 [cm-1]<br> freq ( 5) = 5.074174 [THz] = 169.256234 [cm-1]<br> freq ( 6) = 7.173385 [THz] = 239.278353 [cm-1]<br> freq ( 7) = 7.187844 [THz] = 239.760658 [cm-1]<br> freq ( 8) = 7.251512 [THz] = 241.884398 [cm-1]<br> freq ( 9) = 8.954276 [THz] = 298.682514 [cm-1]<br> **************************************************************************<br><br> Mode symmetry, C_2v (mm2) point group:<br><br> freq ( 1 - 1) = 7.2 [cm-1] --> A_1 D_1 S_1 I+R<br> freq ( 2 - 2) = 8.5 [cm-1] --> B_2 D_4 S_4 I+R<br> freq ( 3 - 3) = 17.0 [cm-1] --> B_1 D_3 S_3 I+R<br> freq ( 4 - 4) = 168.5 [cm-1] --> A_2 D_2 S_2 R <br> freq ( 5 - 5) = 169.3 [cm-1] --> B_2 D_4 S_4 I+R<br> freq ( 6 - 6) = 239.3 [cm-1] --> A_1 D_1 S_1 I+R<br> freq ( 7 - 7) = 239.8 [cm-1] --> B_1 D_3 S_3 I+R<br> freq ( 8 - 8) = 241.9 [cm-1] --> A_1 D_1 S_1 I+R<br> freq ( 9 - 9) = 298.7 [cm-1] --> B_2 D_4 S_4 I+R<br><br></div>Both the pseudos are norm conserving. Clearly, the 1st pseudo detects the mode symmetry correctly. Increasing more harder constraint results the 9 modes to converge and produces the correct dispersion, but the mode symmetry is somehow wrongly read in the 2nd case. I am using QE v 6.1. THere are few options to get rid of imaginary freqencies: Relax the structure well in the order of 10^-6 or less. Do the phonon on a supercell. Change your ASR to a different value. Compare the lattice constants with the available experimental data.<br><br></div>Regards,<br><div><div><div>Sitangshu</div></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 9, 2018 at 5:49 PM, 黄志硕 <span dir="ltr"><<a href="mailto:zhishuohuang@gmail.com" target="_blank">zhishuohuang@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 link="blue" vlink="#954F72" lang="EN-US"><div class="m_8826720864477826134WordSection1"><p class="MsoNormal">Dear Prof. Sitangshu Bhattacharya,</p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Thank you for your reply. But what do you mean by ‘scf report file’? Is it the output file of scf calculation? I don’t see the symmetry information in the output file of scf calculation.</p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">For the pseudopotential, I tested them. The consistent between the AE energy and PS energy is well as well as the logarithmic derivatives. I also tested them in band-structure calculations, and they also produced nearly the same band structures with other PPs provided by quantum espresso PP library. And the phonon dispersion calculated with these PPs seem reasonable.</p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">And by the way, I could not view the pictures you posted.</p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Best regards</p><p class="MsoNormal">Zhishuo Huang</p><p class="MsoNormal"><u></u> <u></u></p></div></div><br>______________________________<wbr>_________________<br>
Pw_forum mailing list<br>
<a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>
<a href="http://pwscf.org/mailman/listinfo/pw_forum" rel="noreferrer" target="_blank">http://pwscf.org/mailman/<wbr>listinfo/pw_forum</a><br></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><font size="3">**********************************************</font></div><div><font size="3">Sitangshu Bhattacharya (সিতাংশু ভট্টাচার্য), Ph.D<br></font></div><div><font size="3">Assistant Professor,</font></div><div><font size="3">Room No. 2221, CC-1,<br>Nanoscale Electro-Thermal Laboratory,<br>Department of Electrical and Communication Engineering,<br>Indian Institute of Information Technology-Allahabad<br></font></div><font size="3"><span>Uttar Pradesh 211 012</span><br>India<br>Telephone: 91-532-2922000 Extn.: 2131<br>Web-page: <a href="http://profile.iiita.ac.in/sitangshu/" target="_blank">http://profile.iiita.ac.in/sitangshu/</a><br>Institute: <a href="http://www.iiita.ac.in/" target="_blank">http://www.iiita.ac.in/</a><br><br></font></div></div></div></div></div></div></div></div></div></div></div></div>
</div>