Dear QE users.
The research group I am in has started to use the QE package but before the
group has used AO based codes.
Therefore the concern of my questions is maybe trivial to you. I have two
questions and both are connected somehow to
the (ultrasoft)pseudopotentials.
1.) What kind of influence a semicore state in the pseudopotential has on the
calculation. I found some general information of
the comparison of norm-conserving and non norm-conserving (ultrasoft)
pseudopotentials but I don't find any good
written description of the influence of semicore states. Which
properties are altered the
most if using semicore states and what are the advantages and
disadvantages?
2.) Since the systems I have to deal with contain heavy elements the question
arises what kind of influence the spin orbit
coupling has on structural and electronic properties. I found one paper
and the two corresponding potentials for gold
and platinum which incoperate a full relativistic treatment and enable a
calculation including spin-orbit coupling for
the LDA functional. Perhaps I havn't found the example of tutorial but is
there a general procedure to incoperate
SO effects on a GGA or a meta-GGA level yet?
A third question is dealing with the density cutoff.
3.) In the QEwiki is written that a higher density cutoff should be used in the
case of ultrasoft pseudopotentials and it should
be checked that all setting have converged. I have done some
calculations and changed first of all the Ecutoff and after
that the Rhocutoff from four to ten times the Ecutoff. There was no big
influence of the Rhocutoff on the structure and energy
in my particular case. Just to avoid a problem in the future. What
properties are altered the most by using a insufficent Rhocutoff?
Best wishes
Paul
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Paul Jennings
Centre for Hydrogen and Fuel Cell Research
PEMFC Research group
School of Chemical Engineering
The University of Birmingham
Edgbaston, Birmingham B15 2TT (U.K.)
E: PCJ994 at bham.ac.uk
T: 07816644583
W: www.fuelcells.bham.ac.uk
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