Dear all, I have few questions related to the above mentioned PP's.
(1) After generating the PAW and USPP versions of these PP (pslib1.0.0) using
ld1 code provided with q.e.5.1.2, I applied the test script. The output seems
to be fine in the case of USPP but for PAW extra few lines are printed. For
example, in the case of LDA scalar-rel Fe, I get:
Making Fe.pz-n-kjpaw_psl.0.2.4.test.in ... Done !
3 2 3D 1( 7.00) -0.41920 -0.41398 -0.00522 !
Making Fe.pz-n-kjpaw_psl.1.0.0.test.in ... Done
Making Fe.pz-n-rrkjus_psl.0.2.4.test.in ... Done
Making Fe.pz-n-rrkjus_psl.1.0.0.test.in ... Done
Making Fe.pz-spn-kjpaw_psl.1.0.0.test.in ... Done
Making Fe.pz-spn-rrkjus_psl.1.0.0.test.in ... Done
And in the case of Fe-rel I get:
Making Fe.rel-pz-n-kjpaw_psl.0.2.4.test.in ... Done !
3 2 1.5 3D 1( 4.00) -0.42153 -0.41623 -0.00530 !
3 2 2.5 3D 1( 3.00) -0.41137 -0.40618 -0.00519 !
Making Fe.rel-pz-n-kjpaw_psl.1.0.0.test.in ... Done
Making Fe.rel-pz-n-rrkjus_psl.0.2.4.test.in ... Done
Making Fe.rel-pz-n-rrkjus_psl.1.0.0.test.in ... Done
Making Fe.rel-pz-spn-kjpaw_psl.1.0.0.test.in ... Done
Making Fe.rel-pz-spn-rrkjus_psl.1.0.0.test.in ... Done
Similar output obtained for Co PAW. Are these extra printed lines indicative
of some error in the generation?
(2) The charge density cutoff recommended (in the UPF files) for these PP is
about 12 *ecutwfc. This large cutoff for the charge density was also employed
in a recent paper using Fe (pslib0.31) (http://arxiv.org/pdf/1502.01534.pdf) .
However, when I did convergence test for the total energy on a unit cell of
SrFeO3 , and SrCO3, and it looks like 4* ecutwfc is sufficient to achieve
convergence. The convergence in the case of SrFeO3 (pslib0.3, USPP) can be
found here (http://web.mit.edu/myoussef/www/Fe_16e_pslib.pdf). The pink bound
indicates that convergence was achieved within 25 mev/unit cell (5 meV/atom)
at ecutwfc=85 Ry and ecutrho =4 *ecutwfc. It seems to me that the recommend
ecutrho it too strict. Are there other tests that one needs to perform to
check the convergence of charge density cutoff?
(3) The recommended ecutwfc and ecutrho for this set of PP in Pslib do not
change from PAW to USPP and do not depend on the functional. I did preliminary
tests and it seems so far that the values work for GGA also work for LDA
consistent with the recommendation. I wonder if one could test convergence of
ecutwfc and ecutrho for LDA only and apply the outcome to all other semilocal
functionals, or are there cases where one encounters different convergence
depending on the functional.
Thank you in advance for reading and help!
Mostafa Youssef
MIT
Fe_16e_pslib0.3.pdf
Description: Fe_16e_pslib0.3.pdf
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