[Pw_forum] fluctuation in SCF energies of CO adsorbed on Pd110
David Foster
davidfoster751 at yahoo.com
Mon Apr 21 15:04:00 CEST 2014
Thank you again Axel. It was very helpful for me.
Regards
David Foster
Ph.D. Student of Chemistry
--------------------------------------------
On Mon, 4/21/14, Axel Kohlmeyer <akohlmey at gmail.com> wrote:
Subject: Re: [Pw_forum] fluctuation in SCF energies of CO adsorbed on Pd110
To: "PWSCF Forum" <pw_forum at pwscf.org>
Date: Monday, April 21, 2014, 4:59 AM
On Mon, Apr 21, 2014 at 6:28 AM,
David Foster <davidfoster751 at yahoo.com>
wrote:
> Thanks Axel
> Yes, in chemistry wee see always the MOs. But in many
unknown cases, we should calculate the MOs by computations.
To use the codes, we need to define 2S+1. In quantum
chemistry codes we use different spin-multiplicity, and we
choose each one that give smaller energy. What about
plane-wave methods?
where in the schoedinger equation does it say it only works
for
atom-centric basis sets?
> Why choosing spin-polarization causes that the energy
fluctuate so much?
i think you are jumping to conclusions here. have you run
the slab
configuration without the CO molecule. charge sloshing can
happen for
all kinds of reasons, and usually it is affected by the
amount of
mixing used and not so much by doing LSDA, but using LSDA
does offer
additional degrees of freedom for the electronic system to
evolve and
thus can emphasize problems like charge sloshing.
> If I compare these two calculations (one with
spin-polarization and one without it), I should get the same
energy. Is it right?
only if there is no magnetization.
axel.
> Thanks again
> Any help will be appreciated.
>
> Regards
>
> David Foster
>
> Ph.D. Student of Chemistry
>
> --------------------------------------------
> On Mon, 4/21/14, Axel Kohlmeyer <akohlmey at gmail.com>
wrote:
>
> Subject: Re: [Pw_forum] fluctuation in SCF
energies of CO adsorbed on Pd110
> To: "PWSCF Forum" <pw_forum at pwscf.org>
> Date: Monday, April 21, 2014, 1:17 AM
>
> On Mon, Apr 21, 2014 at 12:03 AM,
> David Foster <davidfoster751 at yahoo.com>
> wrote:
> > Dear Yun
> > Thanks for your rapid answer. Considering
your answer,
> I have two more questions:
> >
> > 1- In the system I have carbon monoxide.
carbon atom
> has 4 electron in its valance. between O and C
there is a
> triple bond. So, carbon may have one unpaired
electron that
> needs spin-polarization defined. Is it right?
>
> wrong. electrons cannot be "assigned" to
individual atoms,
> they occupy
> "molecular" orbitals. please help yourself to a
little
> quantum
> chemistry refresher.
>
> > 2- Surface of metals due to the charge
density near to
> the surface needs spin-polarization. Is it
right?
>
> wrong. you need spin polarization only if you
have unpaired
> electrons..
>
> > One more point. I have prepared input with
one
> graphical program. When I see the input file with
XCrysDen,
> in the primitive form everything is OK, but in
conventional
> form, three to four Pd atoms in the edge of cell
seems to be
> missing!!!!
>
> that is just visualization. probably your initial
geometry
> has some
> rounding errors in the positions.
>
> axel.
>
> > Regards
> >
> > David Foster
> >
> > Ph.D. Student of Chemistry
> >
> >
--------------------------------------------
> > On Sun, 4/20/14, Yun Wang <yun.wang at griffith.edu.au>
> wrote:
> >
> > Subject: Re: [Pw_forum] fluctuation in
SCF
> energies of CO adsorbed on Pd110
> > To: "PWSCF Forum" <pw_forum at pwscf.org>
> > Date: Sunday, April 20, 2014, 2:41 PM
> >
> > Hi David,I think
> > you need not consider the spin
polarization for
> this system,
> > which will accelerate the
> > convergancy.Cheers,Yun
> >
> >
> >
> >
> >
> > On Mon, Apr 21, 2014
> > at 2:20 AM, David Foster <davidfoster751 at yahoo.com>
> > wrote:
> >
> >
> > Dear users
> >
> >
> >
> > I have prepared an input for
interaction between
> CO and
> > Pd(110). I optimized 3*3*3 supercell
of Pd bulk,
> and then
> > cleaved a 110 surface and constructed
a slab. I
> inserted CO
> > molecule which has been optimized with
QE5.0.2 in
> it. Now, I
> > try to optimize this mixed system
(CO+Pd(110)).
> >
> >
> >
> >
> >
> > My main problem is that in scf I see
the
> fluctuation in
> > energies. My input and output has been
attached.
> In all
> > calculations I used QE5.0.2 and the
same USPP. I
> used PBE
> > DFT in the PP. I used nspin=2 due to
the presence
> of oxygen
> > atom. I introduced start_magnetization
for all
> species. I
> > fixed three bottom layers in the cell.
I used
> ibrav=14 to
> > optimize bulk phase of Pd, and didn't
change it
> in all
> > computation.
> >
> >
> >
> > I used degauss=0.001RY. In addition I
used
> smearing
> > technique for both bulk and slab.
> >
> >
> >
> > The run is continuing, but I think
finally, I
> will encounter
> > with problem.
> >
> >
> >
> > Any idea for rapid convergence and
solve the
> issue in
> > fluctuation energy is appreciated.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Regards
> >
> >
> >
> > David Foster
> >
> >
> >
> > Ph.D. Student of Chemistry
> >
_______________________________________________
> >
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> >
> > Pw_forum at pwscf.org
> >
> > http://pwscf.org/mailman/listinfo/pw_forum
> >
> >
> >
> > --
> >
> > Dr. Yun Wang
> > Research Fellow
> > Centre for Clean Environment and
Energy
> > Griffith School of Environment
> > Gold Coast Campus, Griffith
University
> > QLD 4222, Australia
> > Tel:(61-7) 5552 8456
> > Fax:(61-7) 5552 8067
> >
> >
> >
> >
> > -----Inline Attachment Follows-----
> >
> >
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>
>
> --
> Dr. Axel Kohlmeyer akohlmey at gmail.com
> http://goo.gl/1wk0
> College of Science & Technology, Temple
University,
> Philadelphia PA, USA
> International Centre for Theoretical Physics,
Trieste.
> Italy.
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--
Dr. Axel Kohlmeyer akohlmey at gmail.com
http://goo.gl/1wk0
College of Science & Technology, Temple University,
Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste.
Italy.
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