Hi,<br><br>Can you please elaborate on how you selected your ecutwfc?<br><br>regards,<br><br><div class="gmail_quote">On Mon, Aug 23, 2010 at 10:48 AM, jia chen <span dir="ltr"><<a href="mailto:jiachen@princeton.edu">jiachen@princeton.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">I did similar thing before, total energy doesn't need to converge...<br>
<div><div></div><div class="h5"><br>
On Mon, Aug 23, 2010 at 2:22 AM, Guda Karthik <<a href="mailto:karthik.guda@gmail.com">karthik.guda@gmail.com</a>> wrote:<br>
> Hi,<br>
><br>
> The total energy doesn't converge till 80 Ryd of ecutwfc. I am using Ni<br>
> and Ti USPPs (Ti.pbe-sp-van_ak.UPF, Ni.pbe-nd-rrkjus.UPF). My calculations<br>
> become very slow while using such a large kinetic energy cutoff. am I doing<br>
> something wrong here?<br>
><br>
> regards,<br>
> Karthik<br>
><br>
> On Tue, Aug 17, 2010 at 4:46 PM, Stefano de Gironcoli <<a href="mailto:degironc@sissa.it">degironc@sissa.it</a>><br>
> wrote:<br>
>><br>
>> please note that the two outputs that you submitted ARE NOT examples of<br>
>> vc-relaxation but of structural relaxation of the internal coordinates<br>
>> only. Your question is anyway legittimate...<br>
>> Are you sure to have converged the total energy of your system with<br>
>> respect to cutoff to a sufficient level ?<br>
>> when comparing different volumes one is using different basis sets in<br>
>> the two cases. If convergence w.r.t. cutoff is not sufficient this can<br>
>> lead to sudden decreases of the energy when increasing the volume.<br>
>><br>
>> stefano<br>
>> SISSA and DEMOCRITOS<br>
>><br>
>> Guda Karthik wrote:<br>
>> > Hi,<br>
>> ><br>
>> > Here are the input and output files.<br>
>> ><br>
>> > b19_Acklatpos_new.* - original structure<br>
>> ><br>
>> > b19_pwscf.* - scf calculation with a structure obtained after<br>
>> > vc-relax<br>
>> ><br>
>> > Please have a look if they are of help.<br>
>> ><br>
>> > regards,<br>
>> > Karthik<br>
>> ><br>
>> > On Sat, Aug 14, 2010 at 6:27 AM, Paolo Giannozzi<br>
>> > <<a href="mailto:giannozz@democritos.it">giannozz@democritos.it</a>>wrote:<br>
>> ><br>
>> ><br>
>> >> On Aug 4, 2010, at 4:41 , Guda Karthik wrote:<br>
>> >><br>
>> >><br>
>> >>> I am trying to relax an orthorhombic structure using vc-relax<br>
>> >>> (celldofree - xyz). I start with a structure which is at a Pressure<br>
>> >>> of -20.5 Kbar and at the end of the vc-relax I get a structure<br>
>> >>> which is at a pressure of -0.21 Kbar. Surprisingly, the structure<br>
>> >>> at pressure closer to zero is higher in energy than the original<br>
>> >>> structure by 8 * 10^-4 eV/formula unit. All the symmetry elements<br>
>> >>> have been conserved during relaxation and the initial and final<br>
>> >>> structures are the same. I am not able to make sense of this<br>
>> >>> result. I observe this inconsistency in my B2 structure as well.<br>
>> >>> Please help regarding this.<br>
>> >>><br>
>> >> hard to help without input and output<br>
>> >><br>
>> >> P.<br>
>> >> ---<br>
>> >> Paolo Giannozzi, Dept of Physics, University of Udine<br>
>> >> via delle Scienze 208, 33100 Udine, Italy<br>
>> >> Phone +39-0432-558216, fax +39-0432-558222<br>
>> >><br>
>> >><br>
>> >><br>
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>> >><br>
>> >><br>
>> ><br>
>> ><br>
>> ><br>
>> ><br>
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><br>
><br>
><br>
> --<br>
> Karthik Guda<br>
> Graduate Student<br>
> Materials Engineering<br>
> Purdue University<br>
><br>
><br>
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><br>
<br>
<br>
<br>
--<br>
</div></div>Jia Chen<br>
<br>
Dept of Chemistry<br>
Princeton University<br>
Princeton, NJ 08544<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Karthik Guda<br>Graduate Student<br>Materials Engineering<br>Purdue University<br><br>