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Dear forum,<br>
I'm doing calculations with rrkj pseudo-potentials.<br>
<br>
As far as I understand rrkj are norm-conserving psps and only ecut
should be checked, while ecutrho=4*ecut should be fine.<br>
From this I guess that the ecutrho paramater, if increased, should
not influence the convergence.<br>
<br>
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.<br>
<b>Question 1: Why ?<br>
</b>(I saw that in the psps header Rcut and Rcut US are different
... ?)<br>
<br>
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?).<br>
<b>Question 2: Is there any counter indication in doing that ?<br>
</b><br>
Thanks and best regards,<br>
Davide Sangalli<br>
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