[Pw_forum] atomic making a pp for chromium

[Paolo Giannozzi]

My experience is that lattice parameters and bulk moduli in simple
crystals tend to be better without semicore states than with, but 
in some more complex materials, or in organometallic molecules,
you often need semicore states to get decent results

P.

On Wed, 2013-06-05 at 13:44 +0100, Ben Palmer wrote:
> Hi Giuseppe,
> 
> I've tried the Cr.pbe-sp-van.UPF but my bulk modulus calculation is
> off by about 25-50%.  I've tried a calculation with no magnetisation
> set, nspin=1, and one with a starting magnetisation and nspin=2, but
> the results are quite similar.
> 
>                                                 lattice constant/bohr
> bulk modulus/GPa
> Exp:                                         5.44
> 190
> No starting magnetisation:   5.37
> 257
> With starting magnetism:    5.37
> 257
> 
> I might have made a mistake in my input file, but I was hoping for the
> results to be different.  Would I need to rethink my input or look for
> a new pp?
> 
> All the best,
> 
> Ben
> 
> 
> > Dear Ben
> > 
> > There is a nice USPP for Chromium in the QE online library. It is
> > Cr.pbe-sp-van.UPF and has the 3s and 3p semicore states in valence.
> > I've used it some time ago, and it is as fine as an ultrasoft PP can
> > be...
> > 
> > HTH
> > 
> > Giuseppe
> > 
> > On Tuesday 04 June 2013 23:44:36 Ben Palmer wrote:
> > 
> > > Hi everyone, I've been trying to make a PP for chromium using
> > atomic.
> > 
> > > I've made one so far, but when testing Delta E is quite far out. I
> > was
> > 
> > > hoping to include some of the core electrons, but I'm not sure how
> > to do
> > 
> > > it.
> > 
> > > 
> > 
> > > This is my input script at the moment:
> > 
> > > 
> > 
> > > &input
> > 
> > > title='Cr'
> > 
> > > zed=24.
> > 
> > > iswitch=3,
> > 
> > > nld=10
> > 
> > > rlderiv=2.90,
> > 
> > > eminld=-4.0,
> > 
> > > emaxld=4.0,
> > 
> > > deld=0.01,
> > 
> > > rpwe=2.90,
> > 
> > > rel=1,
> > 
> > > lsmall=.true.,
> > 
> > > dft='PBE',
> > 
> > > verbosity='high',
> > 
> > > file_charge='charge.out',
> > 
> > > config='[Ar] 3d5 4s1 4p0',
> > 
> > > /
> > 
> > > &inputp
> > 
> > > pseudotype=3,
> > 
> > > file_pseudopw='Cr.pbe-sr-uspp-tm.UPF',
> > 
> > > lloc=0,
> > 
> > > nlcc=.true.,
> > 
> > > new_core_ps=.true.,
> > 
> > > tm=.true.,
> > 
> > > rcore=2.0,
> > 
> > > /
> > 
> > > 3
> > 
> > > 3D 3 2 5.00 0.00 1.5 1.5
> > 
> > > 4P 2 1 0.00 0.00 2.5 2.5
> > 
> > > 4S 1 0 1.00 0.00 2.5 2.5
> > 
> > > 
> > 
> > > I also wasn't sure which shell to use for lloc, but varying it
> > hasn't
> > 
> > > made a noticable change to the Delta E on testing.
> > 
> > > 
> > 
> > > Thank you,
> > 
> > > 
> > 
> > > Ben Palmer Student @ University of Birmingham, UK
> > 
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222