The ABINIT Users Mailing List ( CLOSED )

["TORUMBA Doru 218423" <doru.torumba@cea.fr>]

Thank you again for this clarification!

Doru


> -----Original Message-----
> From: Josef W. Zwanziger [mailto:jzwanzig@jzwanzig.org]
> Sent: Tuesday, December 09, 2008 3:27 PM
> To: forum@abinit.org
> Subject: Re: [abinit-forum] alpha-U structure
> 
> Glad that it works. It's not so "strange", though---internally abinit
> applies one element of acell to an entire vector of rprim. In the
cases
> where different acell's are combined, as in body, face, and base
centered
> tetragonal and orthorhombic, you get primitive vectors like
(-a/2,0,c/2)
> and so forth--in these cases, there is no single element of acell that
is
> a common factor, therefore the only choice is to set acell to 1.0 and
then
> carry a, b, and c directly in rprim.
> 
>  Josef W. Zwanziger
> Professor of Chemistry
> Canada Research Chair in NMR Studies of Materials
> Director, Atlantic Region Magnetic Resonance Centre
> Department of Chemistry
> Dalhousie University
> 6274 Coburg Road
> Halifax, Nova Scotia B3H 4J3 Canada
> tel: +1.902.494.1960
> fax: +1.902.494.1310
> web: http://jwz.chem.dal.ca
> jzwanzig@jzwanzig.org,jzwanzig@dal.ca
> 
> 
> 
> ----- Original Message ----
> > From: TORUMBA Doru 218423 <doru.torumba@cea.fr>
> > To: forum@abinit.org
> > Sent: Tuesday, December 9, 2008 10:07:02 AM
> > Subject: RE: [abinit-forum] alpha-U structure
> >
> > Dear Joe,
> >
> > Thank you very much for the tip! Strange enough, but it works!
> >
> > Best regards,
> > Doru
> >
> >
> > > -----Original Message-----
> > > From: Josef W. Zwanziger [mailto:jzwanzig@jzwanzig.org]
> > > Sent: Tuesday, December 09, 2008 2:54 PM
> > > To: forum@abinit.org
> > > Subject: Re: [abinit-forum] alpha-U structure
> > >
> > > Dear Doru,
> > >
> > > what always seems to work best in these face and base-centered
> > structures
> > > is to set acell to 1.0 and carry the vector lengths in rprim. This
is
> > due
> > > to the way abinit will combine these variables internally. So in
your
> > case
> > > I would try
> > >
> > > acell 3*1.0
> > > rprim 2.695 5.552 0.000
> > >      -2.695 5.552 0.000
> > >       0.000 0.000 9.3274
> > >
> > > let me know if this doesn't work--
> > > Joe
> > >
> > >  Josef W. Zwanziger
> > > Professor of Chemistry
> > > Canada Research Chair in NMR Studies of Materials
> > > Director, Atlantic Region Magnetic Resonance Centre
> > > Department of Chemistry
> > > Dalhousie University
> > > 6274 Coburg Road
> > > Halifax, Nova Scotia B3H 4J3 Canada
> > > tel: +1.902.494.1960
> > > fax: +1.902.494.1310
> > > web: http://jwz.chem.dal.ca
> > > jzwanzig@jzwanzig.org,jzwanzig@dal.ca
> > >
> > >
> > >
> > > ----- Original Message ----
> > > > From: Doru Torumba
> > > > To: forum@abinit.org
> > > > Sent: Tuesday, December 9, 2008 9:20:27 AM
> > > > Subject: [abinit-forum] alpha-U structure
> > > >
> > > > Dear Abinit users,
> > > >
> > > > I am trying to create the alpha-U structure, but for some reason
I
> > do
> > > not get
> > > > the correct space group (Cmcm, #63). In this structure there are
2
> > atoms
> > > per
> > > > unit cell. Atomic positions are (y,-y,-1/4) and (-y,y,1/4) in
units
> > of
> > > Bravais
> > > > lattice vectors defined by (a/2,-b/2,0),  (a/2,b/2,0), (0,0,c).
> > Instead
> > > I get
> > > > the space group  P2_1/m (#11). Most probably I am overlooking
> > something
> > > > obvious, but I can't figure out what. Suggestions are welcome :)
> > > >
> > > > #Definition of the unit cell
> > > > acell 5.39 11.1034 9.3247
> > > >
> > > > rprim  0.5  0.5  0.0   # primitive vectors
> > > >       -0.5    0.5  0.0
> > > >        0.0    0.0  1.0
> > > >
> > > > #Definition of the atom types
> > > > ntypat 1      # No of atom types
> > > > znucl 92
> > > >
> > > > #Definition of the atoms
> > > > natom 2               # No of atoms in the cell
> > > > typat 1 1              # Type of each atom
> > > >
> > > > xred
> > > >     0.10 -0.10    -0.25
> > > >    -0.10  0.10     0.25
> > > >
> > > > #Definition of the planewave basis set
> > > > ecut 35
> > > > pawecutdg 40
> > > >
> > > > #Exchange-correlation functional
> > > > ixc 11 #GGA (PBE)
> > > >
> > > > #Definition of the k-point grid
> > > > kptopt 1
> > > >
> > > > ngkpt 2 2 2
> > > > tsmear 0.001
> > > >
> > > > #Spin polarization
> > > > nsppol 1
> > > >
> > > > #Definition of occupation numbers
> > > > occopt 3
> > > > nband 40
> > > >
> > > > #Definition of the SCF procedure
> > > > nstep 100
> > > > usepaw 1
> > > > toldfe 1.0d-6
> > > > iscf 7