Dear Yuva,<br><br>I believe you should test the convergence of the total energy as those parameters vary. Usually, ecutrho should be between 8 to 14 times the value of ecutwfc, depending on the material. For example, you could run a scf calculation using, say, ecutwfc=30, ecutrho=300, then again with ecutwfc=40, ecutrho=400 and so on, and check the total energy convergence. Then given a value of ecutwfc, you can vary ecutrho to see which values lead to convergence. This is needed in order to find a setup that mixes precision with computational cost well. If, on the other hand, you don't care about computational cost, then you could use, say, ecutwfc=200 and ecutrho=2800 and I'm pretty sure you'll have a well converged calculation, altough it'd take a very long time to evaluate it (or not, if you can use a very powerful computer).<br>
<br>Best,<br><br>Giovani M. Faccin<br>UFMS/Unicamp - Brazil<br><br><br><br><div class="gmail_quote">2011/6/8 yuva rani <span dir="ltr"><<a href="mailto:syuva2987@gmail.com">syuva2987@gmail.com</a>></span><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
On 6/8/11, yuva rani <<a href="mailto:syuva2987@gmail.com">syuva2987@gmail.com</a>> wrote:<br>
> I am trying to relax a gold surface consisting of 112 atoms. I encountered<br>
> a<br>
> error in the output file as negative rho (up, down). I need the guidence of<br>
> the ecutwfc for gold and how to set this value.<br>
> *Thank you and Regards,<br>
> **<br>
> ** S.Yuva<br>
> ** Physics Department<br>
> ** Bharathiar University.*<br>
><br>
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</blockquote></div><br><br clear="all"><br>-- <br>Giovani<br>