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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">Dimpy:<o:p></o:p></span></p>
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color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">DFT usually scales as N^3 so I’d guess that it will take 5**3=125 times longer than the small system. You would probably gain somewhere due to fewer k-Points,
etc. but that’s my rough estimate.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">Others may have other comments that I welcome…<o:p></o:p></span></p>
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color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">Mike<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><a href="mailto:michael@ihpc.a-star.edu.sg">michael@ihpc.a-star.edu.sg</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><a href="http://www.sullivan.sg/">http://www.sullivan.sg/</a>
<o:p></o:p></span></p>
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color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> pw_forum-bounces@pwscf.org [mailto:pw_forum-bounces@pwscf.org]
<b>On Behalf Of </b>Dimpy Sharma<br>
<b>Sent:</b> Tuesday, July 20, 2010 9:41 PM<br>
<b>To:</b> pw_forum@pwscf.org<br>
<b>Subject:</b> [Pw_forum] Predicting the cpu time usage for bigger system withour doing the simulation<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Hi Quantum espresso users.</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">I would like to predict an approximate CPU time usage to finish one scf calculation in quantum espresso for a system with 5 supercells. I have the CPU time usage for the same
sytem with one supercell.So are there any possible ways to predict the time needed for more number of supercell (for the same system) required in quantum espresso,without doing the simulations.Can I calcuate it from the following method
</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif"">T<sub>scf</sub>= N<sub>iter</sub>T<sub>iter</sub> + T<sub>init</sub></span><span style="font-family:"Arial","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:black">Thanks and Regards.</span><o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Dimpy</span><o:p></o:p></p>
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<pre>Dimpy Sharma<o:p></o:p></pre>
<pre>ETG-Group<o:p></o:p></pre>
<pre>Tyndall National Institute<o:p></o:p></pre>
<pre>Cork<o:p></o:p></pre>
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