[Pw_forum] problem with ibrav=13 again

[Stefano de Gironcoli]

one possibility cound be  to use ibrav=0 and then provide the bravais 
lattice vector as required by your cell via the
CELL_PARAMETERS card...
Hope this helps
stefano

hania djani-ait aissa wrote:
> thanks for reply,
> actually, the problem is that the data collected by neutron 
> diffraction gives a non-standard A2/m structure with a=8.37Angstrom, 
> b=3.85A. c=16.44 and Beta >90°=102.334°. for pwscf recognize my 
> structure i had to transforme A2/m to C2/m by swapping a and c axis 
> and swapping x and z coordinates. however pwscf gives for ibrav=13 
> celldm(4)=cos(gamma) and my angle is Beta between ac.
>
> hania
> > From: tone.kokalj at ijs.si
> > To: pw_forum at pwscf.org
> > Date: Wed, 4 Feb 2009 13:26:02 +0100
> > Subject: Re: [Pw_forum] problem with ibrav=13 again
> >
> > On Wed, 2009-02-04 at 11:23 +0000, hania djani-ait aissa wrote:
> > > Dear all,
> > > thank you for your quick reply, the structure should look as stacked
> > > multilayers of Bi2O2 slabs and perovskites ones along a-axis. i will
> > > use the latest version of Xcrysden and check if the problem still
> > > persist. here my total input file:
> >
> > Based on your input, I just checked that the new xcrysden version uses
> > the lattice for ibrav=13 as specified in the pwscf documentation for
> > ibrav13, i.e.:
> >
> > celldm(1)=a, celldm(2)=b/a, celldm(3)=c/a, celldm(4)=cos(ab)
> >
> > v1 = ( a/2, 0, -c/2),
> > v2 = (b*cos(gamma), b*sin(gamma), 0),
> > v3 = ( a/2, 0, c/2),
> >
> > where gamma is the angle between axis a and b
> >
> > There is indeed some problem in your structure: some Bi and O atoms are
> > too close (only 1.1 Angs). Please check the coordinates of atoms 5, 6, 7
> > and 8 (in particular the two oxygens).
> >
> > Regards, Tone
> > --
> > Anton Kokalj
> > J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
> > (tel: +386-1-477-3523 // fax:+386-1-477-3822)
> >
> > Please, if possible, avoid sending me Word or PowerPoint attachments.
> > See: http://www.gnu.org/philosophy/no-word-attachments.html
> >
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