Hi,<br>The USPP which includes sp semicore could lead you to that such ecut if it is not a very good PP. Ecutrho should be about 10-14*ecut and you should also make sure that the k-point sampling is good enough.<br>Good luck.<br>
<br><div class="gmail_quote">On Wed, Sep 30, 2009 at 2:15 PM, Ary Junior <span dir="ltr"><<a href="mailto:aryjunior@gmail.com">aryjunior@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi Lorenzo, I did exactly what you said and I got the same convergence chart on both tests... I'm working with g-alumina and ultrasoft pp... My first convergence test suggested an ecutwfc value between 50Ry-70Ry... Then I used ecutrho = 280Ry for the second test... It means that I can use ecutrho = 4*ecutwfc, right?<br>
<br>[]s<br><br>Ary Junior<div><div></div><div class="h5"><br><br><div class="gmail_quote">On Wed, Sep 30, 2009 at 1:00 PM, Lorenzo Paulatto <span dir="ltr"><<a href="mailto:paulatto@sissa.it" target="_blank">paulatto@sissa.it</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
In data 30 settembre 2009 alle ore 17:48:41, udayagiri sai babu<br>
<<a href="mailto:udayagiri3@gmail.com" target="_blank">udayagiri3@gmail.com</a>> ha scritto:<br>
<div><br>
> Dear all<br>
> I did convergence tests for chromium. The ecut value i obtained for<br>
> energy converged to 1mRyd is 60Ryd! which i believe is very high for an<br>
> Ultra Soft PP can somebody tell me if i am doing something wrong. Given<br>
> below are my<br>
> sample input file and ecut vs total energy.<br>
<br>
</div>Dear Udayagiri,<br>
what about the cutoff for charge density?<br>
One good procedure to find a nicely converged cutoff is to increase<br>
ecutwfc until it converges than set ecutrho to 4*ecutwfc and reduce<br>
ecutwfc keeping ecutrho fixed.<br>
<br>
Maybe you can fix ecutrho to 240 and see how low you can go with ecutwfc<br>
<br>
best regards<br>
<br>
<br>
--<br>
Lorenzo Paulatto<br>
SISSA & DEMOCRITOS (Trieste)<br>
phone: +39 040 3787 511<br>
skype: paulatz<br>
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<br>
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