<div dir="ltr">If you want to compute electron-phonon interaction for a phonon of wavevector q, you will need electron wavefunctions at k and k+q. Thus your grid for scf should always be a multiple of your q-point grid for phonon calculations. Since 8 is a multiple of 2 and 4 but not 6, you are getting this error. Hope that helps.<div>
Sridhar</div><div>Purdue University</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sun, Jun 1, 2014 at 9:36 AM, Peram sreenivasa reddy <span dir="ltr"><<a href="mailto:peramsreenivas@gmail.com" target="_blank">peramsreenivas@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>Dear Pwscf,<br><br><br></div>In my phonon calculations i got some error.<br><br></div><div>For nq1=2, nq2=2, nq3=2 and nq1=4, nq2=4, nq3=4 i did not get any errors.<br>
<br></div><div>But for nq1=6, nq2=6, nq3=6 grid i got the bellow error.<br>
</div><br><div><div>Diagonalizing the dynamical matrix<br><br> q = ( -0.166666667 0.166666667 -0.166666667 ) <br><br> **************************************************************************<br> omega( 1) = 1.218152 [THz] = 40.633179 [cm-1]<br>
omega( 2) = 1.218152 [THz] = 40.633179 [cm-1]<br> omega( 3) = 2.760322 [THz] = 92.074433 [cm-1]<br> omega( 4) = 3.157206 [THz] = 105.313054 [cm-1]<br> omega( 5) = 3.157206 [THz] = 105.313054 [cm-1]<br>
omega( 6) = 3.160843 [THz] = 105.434373 [cm-1]<br> omega( 7) = 6.119555 [THz] = 204.126381 [cm-1]<br> omega( 8) = 6.129602 [THz] = 204.461528 [cm-1]<br> omega( 9) = 6.129602 [THz] = 204.461528 [cm-1]<br>
omega(10) = 9.495441 [THz] = 316.733825 [cm-1]<br> omega(11) = 9.521102 [THz] = 317.589790 [cm-1]<br> omega(12) = 9.521102 [THz] = 317.589790 [cm-1]<br> **************************************************************************<br>
<br> Mode symmetry, C_3v (3m) point group:<br><br> omega( 1 - 2) = 40.6 [cm-1] --> E L_3 <br> omega( 3 - 3) = 92.1 [cm-1] --> A_1 L_1 <br> omega( 4 - 5) = 105.3 [cm-1] --> E L_3 <br>
omega( 6 - 6) = 105.4 [cm-1] --> A_1 L_1 <br> omega( 7 - 7) = 204.1 [cm-1] --> A_1 L_1 <br> omega( 8 - 9) = 204.5 [cm-1] --> E L_3 <br>
omega( 10 - 10) = 316.7 [cm-1] --> A_1 L_1 <br> omega( 11 - 12) = 317.6 [cm-1] --> E L_3 <br><br> **************************************************************************<br>
electron-phonon interaction ...<br><br><br> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br> from elphsum : error # 3<br> q is not a vector in the dense grid<br> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
<br> stopping ...<br><br> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br> from elphsum : error # 3<br> q is not a vector in the dense grid<br> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
<br clear="all"><div>This error came after completing my first q point. <br><br><br></div><div>Is this q grid is correct for the given k points mesh?<br><br></div><div>Is it better to increase it to nq1=8, nq2=8, nq3=8. ?<br>
<br></div><div>Thank you very much in advance.<span class="HOEnZb"><font color="#888888"><br><br><br><br><br></font></span></div><span class="HOEnZb"><font color="#888888"><div><br><br><br>-- <br><i>P.V.SREENIVASA REDDY</i><br>
<i>Research Scholar<br>Department of Physics </i><br><br></div></font></span></div></div></div>
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