The ABINIT Users Mailing List ( CLOSED )

[Josef Zwanziger <jzwanzig@dal.ca>]

As I said, I don't do research on f-block elements so I haven't done any
optimization, it's just based directly on what CASTEP uses. If you can
improve on those parameters, great!

Joe

On Thu, 2007-06-07 at 14:23 +0800, zaq Liu wrote:
> Dear Prof. Joe,
> 
> Thank you very much  for your  pseudopotential .
> Why do you use  5s2 5p6 6s2 4f8 as valence but not 5s2 5p6 6s2 4f7 5d1 ?
> And I find your rc=2.1 ( if I understand correctly), why is it so small ?
> The half of distance is often  2.8-3.2. The small rc need a high ecut,
> I check it need about 30Ha.is it right ? while our rc=3.0 need 16 Ha.
> In addition, when I use Custom rrkj rather than Vanderbilt, the SCF
> loops can obtain convergence for both hcp Gd and GdN. If iprcel= 49
> and diemix = 0.5 are applied , the convergence becomes much faster
> (about 50 times).
> The optimized lattice constance for GdN is less than the exp. values by 3%.
> 
> Best regards,
> 
> Bo Liu
> 
> 
> 
> 2007/6/7, Josef Zwanziger <jzwanzig@dal.ca>:
> > Hi,
> >
> > I've attached the input files for USpp2abinit I made for gadolinium,
> > using as inspiration the Vanderbilt ultra-soft pseudopotential for Gd
> > distributed with CASTEP. It uses as valence 5s2 5p6 6s2 4f8, with two
> > projectors in each channel (s, p, f) and l=2 for the local channel.
> > Using it with abinit 5.3.4, Gd metal SCF converges ok but needs a lot
> > of empty states and is quite sensitive to tsmear (I use occopt = 4). GdN
> > was easier to converge and also optimized its structure very well. On
> > the other hand, Gd structure did not optimize. Because this
> > pseudopotential uses 18 electrons in valence with two projectors, it is
> > very flexible but consumes a lot of memory. I don't do research on
> > f-block elements so I haven't really pursued this, but thought it might
> > be of interest to supply a USPP-based PAW data set to the discussion to
> > compare with Atompaw-based PAW.
> >
> > Joe
> >
> > On Wed, 2007-06-06 at 16:49 +0200, Anglade Pierre-Matthieu wrote:
> > > Hi,
> > >
> > > What you are saying appears quite weird without having a look at your
> > > input file. Would you mind telling us a little bit more (for instance
> > > showing abinit's input and output) ?
> > > By the way, if the SCF convergence of your system is really as
> > > difficult as you describe it I'm very much interested in having a look
> > > at it. I would be very grateful if you share with me pseudopotentials
> > > and input file.
> > >
> > > Regards
> > >
> > > PMA
> > >
> > > On 6/5/07, zaq Liu <iloveabinit@gmail.com> wrote:
> > >         Dear Dr. Marc Torrent,
> > >
> > >         Thank you very much for your suggestion.
> > >         I find that rc=3.2 seems to be reasonable for hcp Gd metal.
> > >         3.2 is a little smaller than the half of the distance for two
> > >         Gd ions (3.37).
> > >         The relaxed lattice constant is very close to the exp. values
> > >         (smaller by 2%)
> > >         But during the calculation,the SCF loops need about 200-300
> > >         times.
> > >         Furthermore, when I calculate GdN and GdP, the SCF loops never
> > >         reach
> > >         convergence after 350 times. I try a number of variables
> > >         diemac dielng
> > >         and iprcel and iscf 14, 17 , but the situation does not
> > >         change.
> > >         Could you please give me some useful advice how to improve the
> > >         atomic
> > >         data for Gd?
> > >         Thank you very much!
> > >
> > >         Best regards,
> > >
> > >         Bo Liu
> > >
> > >         2007/6/1, Marc Torrent <marc.torrent@cea.fr>:
> > >         > Quick answer, with some key ideas:
> > >         >
> > >         > - you should verify your log derivatives and eventually
> > >         change the
> > >         > reference energy (especially for d, f electrons).
> > >         > - your high cut-off is a sign of a small pseudization
> > >         radius ; are you
> > >         > sure of the rc=2. or 2.2 ? I think you should obtain
> > >         reasonnable values
> > >         > for ecut with rc=2.4.
> > >         >
> > >         > Marc Torrent
> > >         >
> > >         >
> > >         > iloveabinit@gmail.com a écrit :
> > >         > > Dear All,
> > >         > >
> > >         > > I generate the Gd atomicdata using atompaw code.
> > >         > > The calculated lattice constants  of hcp Gd and GdN show
> > >         > > a very large errors (smaller than the experimental values
> > >         by about 15%).
> > >         > > The LDA and GGA show the similar results. Also the ecut
> > >         needed is about 28 Ha when the total energy difference is
> > >         smaller than 1meV/atom. Is this ecut too high ? I know the
> > >         common ecut for PAW is about 15 Ha.
> > >         > >
> > >         > > The input file is attached below. The attached file uses
> > >         rc=2.0, I also test rc=2.2 and get the same result. I am
> > >         appreciated for any useful advice!
> > >         > >
> > >         > > Bo Liu
> > >         > >
> > >         > > INPUTFILE
> > >         > >
> > >         > > Gd 64  #1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 (5s2 5p6 4f7
> > >         5d1 6s2)
> > >         > > LDA-PW scalarrelativistic loggrid 2001
> > >         > > 6 5 5 4 0
> > >         > > 4 3 7
> > >         > > 5 2 1
> > >         > > 0 0 0
> > >         > > c
> > >         > > c
> > >         > > c
> > >         > > c
> > >         > > v
> > >         > > v
> > >         > > c
> > >         > > c
> > >         > > c
> > >         > > v
> > >         > > c
> > >         > > c
> > >         > > v
> > >         > > v
> > >         > > 3
> > >         > > 2.0 2.0 2.0 2.0   #rc rpaw
> > >         > > n
> > >         > > y
> > >         > > 2
> > >         > > n
> > >         > > y
> > >         > > 3
> > >         > > n
> > >         > > y
> > >         > > 5
> > >         > > n
> > >         > > Vanderbilt
> > >         > > 4 0
> > >         > > 2.0
> > >         > > 2.0
> > >         > > 2.0
> > >         > > 2.0
> > >         > > 2.0
> > >         > > 2.0
> > >         > > 2.0
> > >         > > 2.0
> > >         > > 0
> > >         > >
> > >         > >
> > >         > >
> > >         > >
> > >         >
> > >
> > >
> > >
> > >
> > > --
> > > Pierre-Matthieu Anglade
> > --
> > Josef W. Zwanziger
> > Prof. of Chemistry and
> >  Canada Research Chair in NMR Studies of Materials
> > Director, Atlantic Region Magnetic Resonance Centre
> > Dept. of Chemistry
> > Dalhousie University
> > Halifax, NS B3H 4J3 Canada
> > Tel: +1 (902) 494-1960
> > Fax: +1 (902) 494-1867
> > Net: jzwanzig@dal.ca
> > Web: http://jwz.chem.dal.ca
> >
> >
> 
-- 
Josef W. Zwanziger
Prof. of Chemistry and 
 Canada Research Chair in NMR Studies of Materials
Director, Atlantic Region Magnetic Resonance Centre
Dept. of Chemistry
Dalhousie University
Halifax, NS B3H 4J3 Canada
Tel: +1 (902) 494-1960
Fax: +1 (902) 494-1867
Net: jzwanzig@dal.ca
Web: http://jwz.chem.dal.ca