[Pw_forum] problem with ibrav=13 again

[hania djani-ait aissa]

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> > _______________________________________________> Pw_forum mailing list> Pw_forum at pwscf.org> http://www.democritos.it/mailman/listinfo/pw_forum
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