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rrkjus refers to an US pseudopotential geerated in two steps. first
a hard NCPP is generated according to the rrkj recipe and then an
USPP is generated whose augmentation charges reproduce the one of
the previous NCPP.<br>
<br>
stefano <br>
<br>
On 01/31/2011 01:31 PM, Davide Sangalli wrote:
<blockquote cite="mid:4D46AB9E.20504@gmail.com" type="cite">
<pre wrap="">Thanks for the answers to question 1.
So rrkjus from quantum espresso are not norm conserving (indeed I'm using rrkjus
psps).
I supposed that rrkj means a pseudo created according to the rrkj scheme
presented in PRB 41, 1227 (1990).
In that paper the proposed psps are norm-conserving. Is that correct?
Is there any another paper I should look for?
Regards,
Davide
On 01/31/2011 12:41 PM, Davide Sangalli wrote:
> Dear forum,
> I'm doing calculations with rrkj pseudo-potentials.
>
> As far as I understand rrkj are norm-conserving psps and only ecut should be
> checked, while ecutrho=4*ecut should be fine.
> From this I guess that the ecutrho paramater, if increased, should not
> influence the convergence.
>
> I did some test and I saw that this is not true. Increasing ecutrho (at fixed
> ecut) the results changes significantly. For example the elements of the
> stress tensor changes more than 15 Kbar (in some case even more) moving
> ecutrho from 140 to 300 Ry (with ecut=35 Ry). Here I was testing FeO, CoO and
> NiO, with pbe/rrkj psps for all thee elements.
> *Question 1: Why ?
> *(I saw that in the psps header Rcut and Rcut US are different ... ?)
>
> I did these checks even because I would like to perform calculations using
> vanderbilt psp (for some elements) together with rrkj psp (for other element?).
> *Question 2: Is there any counter indication in doing that ?
> *
> Thanks and best regards,
> Davide Sangalli
</pre>
<pre wrap="">
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