Dear Jia,<div><br></div><div>I checked those pp and there are not recommended cutoffs. When I use occupation=fixed, the results are similar as those from occupation=smearing (reach minimum at 80 Ry) . And the scf doesn't converge when ecutwfc=60 Ry.</div>
<div><br></div><div>Ecutwfc energy total force</div><div><div>50<span style="white-space:pre-wrap"> </span>-1129.7209 <span style="white-space:pre-wrap"> </span>0.7937 </div><div>60<span style="white-space:pre-wrap"> </span>no converge<span style="white-space:pre-wrap">nce</span></div>
<div>70<span style="white-space:pre-wrap"> </span>-1136.6081 <span style="white-space:pre-wrap"> </span>0.7066 </div><div>80<span style="white-space:pre-wrap"> </span>-1137.3776 <span style="white-space:pre-wrap"> </span>0.7059 </div>
<div>90<span style="white-space:pre-wrap"> </span>-1137.3342 <span style="white-space:pre-wrap"> </span>0.6997 </div><div>100<span style="white-space:pre-wrap"> </span>-1136.9523 <span style="white-space:pre-wrap"> </span>0.7056 </div>
<br><div class="gmail_quote">On Mon, Sep 10, 2012 at 5:17 PM, Jia Chen <span dir="ltr"><<a href="mailto:jiachenchem@gmail.com" target="_blank">jiachenchem@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear Peng,<br>
<br>
For AFM case, you can set tot_magentization = 0, for FM case, you need<br>
to know tot_magnetization from experiments or previous calculations.<br>
Or you can use the int(absolute magnetization) from you AFM<br>
calculations.<br>
<br>
Trying to converge total energy with respect to wave function cutoff<br>
is usually not a good idea. If you just want to choose a good cutoff<br>
energy for calculations, first thing you can do is to look into those<br>
pseudopotentials you are using. If you can find recommended cutoffs,<br>
you probably can just use the highest cutoffs in your system.<br>
<br>
Bests<br>
Jia<br>
<div><div><br>
On Mon, Sep 10, 2012 at 5:02 PM, Peng Chen <<a href="mailto:pchen@ion.chem.utk.edu" target="_blank">pchen@ion.chem.utk.edu</a>> wrote:<br>
> Dear Dr. Giannozzi,<br>
><br>
> Thanks for your reply. I use smearing for computing the band structure in<br>
> afm and fm states. It looks there is still a lot to learn. If I use<br>
> occupation=fixed to calculate afm/fm states, shall I just set<br>
> tot_magnetization=0 or 1?<br>
><br>
> If I didn't set ecutrho, the default value of ecutrho is 4*ecutwfc. So the<br>
> results are the same as the following, and the energy doesn't decrease<br>
> monotonically. I tried to decrease degauss to 0.005 Ry, I got the similar<br>
> results. What I can do to make the energy converge?<br>
><br>
> ecutrho=4*ecutwfc<br>
> ecutwfc energy total force<br>
> 30 -1086.672528 1.335253<br>
> 40 -1119.972723 0.690327<br>
> 50 -1129.973333 0.690484<br>
> 60 -1134.622157 0.640747<br>
> 70 -1136.892534 0.617201<br>
> 80 -1137.666471 0.616635<br>
> 90 -1137.620919 0.610216<br>
> 100 -1137.238099 0.615361<br>
> 110 -1136.89911 0.62063<br>
> 120 -1136.866006 0.622763<br>
><br>
> On Mon, Sep 10, 2012 at 3:45 PM, Paolo Giannozzi <<a href="mailto:giannozz@democritos.it" target="_blank">giannozz@democritos.it</a>><br>
> wrote:<br>
>><br>
>><br>
>> On Sep 10, 2012, at 16:35 , Peng Chen wrote:<br>
>><br>
>> > I tried to calculate an insulator Ni3V2O3 using pbe norm conserving<br>
>> > pp from pslibrary. But the energy related with ecutwfc is not<br>
>> > converged. It reaches minimum at ecutwfc=80 Ry. But when I fix<br>
>> > ecutrho=320 Ry and increase ecutwfc, it starts to decrease<br>
>> > monotonically. I am not sure if the system reaches the convergence<br>
>> > at ecutwfc=80 Ry.<br>
>> > (smearing=mv, Degauss=0.01 Ry and kpoints = 4 4 3)<br>
>><br>
>> if it is an insulator, why are you using smearing? Apart from this:<br>
>> with norm-conserving PP, ecutwfc is the only parameter defining<br>
>> the basis set. You should not set ecutrho.<br>
>><br>
>> P.<br>
>> ---<br>
>> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,<br>
>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>
>> Phone <a href="tel:%2B39-0432-558216" value="+390432558216" target="_blank">+39-0432-558216</a>, fax <a href="tel:%2B39-0432-558222" value="+390432558222" target="_blank">+39-0432-558222</a><br>
>><br>
>><br>
>><br>
>><br>
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><br>
><br>
><br>
><br>
> --<br>
> Best Regards.<br>
> Peng<br>
><br>
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<br>
<br>
<br>
--<br>
</div></div><span><font color="#888888">Jia Chen<br>
webpage: <a href="http://www.princeton.edu/~jiachen" target="_blank">www.princeton.edu/~jiachen</a><br>
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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br> Best Regards.<br> Peng <br>
</div>