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<p class="MsoNormal">Dear All!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am currently looking into phonon calculations and I am a bit confused by the available methods of parallelization and their applicability to my system.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I read chapter 5 (Parallelism) <a href="http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide/node10.html">
http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide/node10.html</a> and I briefly checked the paper on the GRID example.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The machine I want to run the job on is a local ¡°supercomputer¡± (25,408 Intel Xeon CPUs on 3,176 nodes) so I guess resources should not be a problem – unfortunately I am the only person in my group doing this and I am pretty clueless¡¦<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am specifically trying to find out how to choose –np –ni and –nk, so that the calculation doesn¡¯t complain about some processor not having a wavefunction or k-point.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My unit cell is cubic and has 5 atoms of 3 types. I calculate scf on a fine (12 12 12 0 0 0) and coarse (6) k-grid for la2f calculations. Then I use ph.x on a (6 6 6) q-grid (I am following a tutorial I found on this mailing list).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">During the ph.x test- run on a single cpu for testing I find that
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> There are 5 irreducible representations<o:p></o:p></p>
<p class="MsoNormal"> There are 10 irreducible representations<o:p></o:p></p>
<p class="MsoNormal"> There are 10 irreducible representations<o:p></o:p></p>
<p class="MsoNormal"> There are 10 irreducible representations<o:p></o:p></p>
<p class="MsoNormal"> There are 15 irreducible representations<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">And <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> number of k points= 20 <o:p></o:p></p>
<p class="MsoNormal"> number of k points= 120 <o:p></o:p></p>
<p class="MsoNormal"> number of k points= 120 <o:p></o:p></p>
<p class="MsoNormal"> number of k points= 120 <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">irreps (corresponding to images in parallelization) and k-points (npools) constantly change, so I do not understand how to efficiently parallelize this kind of job when submitting, especially since I do not have any a-priori knowledge of
the change of these quantities. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Further <a href="http://training.uhem.itu.edu.tr/docs/18hazirannano/PW-III-para.pdf">
http://training.uhem.itu.edu.tr/docs/18hazirannano/PW-III-para.pdf</a> notes that npool must be a divider of Nk. So the lowest common denominator in above calculation would be: -npool 20 and –nimage 5 ?
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Any comment is greatly appreciated, I am really lost on this!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Yours,<o:p></o:p></p>
<p class="MsoNormal">Chris <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Christoph Wolf<o:p></o:p></p>
<p class="MsoNormal">Postech University, Department of Materials Science and Engineering<o:p></o:p></p>
<p class="MsoNormal">Pohang, South Korea<o:p></o:p></p>
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