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thanks for reply,<BR>
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.<BR><BR>
hania<BR>> From: tone.kokalj@ijs.si<BR>> To: pw_forum@pwscf.org<BR>> Date: Wed, 4 Feb 2009 13:26:02 +0100<BR>> Subject: Re: [Pw_forum] problem with ibrav=13 again<BR>> <BR>> On Wed, 2009-02-04 at 11:23 +0000, hania djani-ait aissa wrote:<BR>> > Dear all,<BR>> > thank you for your quick reply, the structure should look as stacked<BR>> > multilayers of Bi2O2 slabs and perovskites ones along a-axis. i will<BR>> > use the latest version of Xcrysden and check if the problem still<BR>> > persist. here my total input file:<BR>> <BR>> Based on your input, I just checked that the new xcrysden version uses<BR>> the lattice for ibrav=13 as specified in the pwscf documentation for<BR>> ibrav13, i.e.:<BR>> <BR>> celldm(1)=a, celldm(2)=b/a, celldm(3)=c/a, celldm(4)=cos(ab)<BR>> <BR>> v1 = ( a/2, 0, -c/2),<BR>> v2 = (b*cos(gamma), b*sin(gamma), 0),<BR>> v3 = ( a/2, 0, c/2),<BR>> <BR>> where gamma is the angle between axis a and b<BR>> <BR>> There is indeed some problem in your structure: some Bi and O atoms are<BR>> too close (only 1.1 Angs). Please check the coordinates of atoms 5, 6, 7<BR>> and 8 (in particular the two oxygens).<BR>> <BR>> Regards, Tone<BR>> -- <BR>> Anton Kokalj<BR>> J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia <BR>> (tel: +386-1-477-3523 // fax:+386-1-477-3822)<BR>> <BR>> Please, if possible, avoid sending me Word or PowerPoint attachments.<BR>> See: http://www.gnu.org/philosophy/no-word-attachments.html<BR>> <BR>> _______________________________________________<BR>> Pw_forum mailing list<BR>> Pw_forum@pwscf.org<BR>> http://www.democritos.it/mailman/listinfo/pw_forum<BR><BR><br /><hr />Téléchargez le nouveau Windows Live Messenger ! <a href='http://get.live.com/messenger/overview' target='_new'>Téléchargez Messenger, c'est gratuit !</a></body>
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