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<DIV>I have sometimes encoutered this type of problem : starting from
antiparallel spins and using the "runafm" script may lead to a non-magnetic or
to a ferromagnetic solution, even though the ground state turns out to be the
antiferromagnetic one, at last (from the Wien calculations). </DIV>
<DIV>For example, this was the case of TeCuO3 (Chem. Mater. 17, 4350, 2005).
</DIV>
<DIV> </DIV>
<DIV>The trick is then to : </DIV>
<DIV>- check the evolution of the magnetic moments along the iterations, </DIV>
<DIV>- when close to the expected values, stop the "runafm" calculation,</DIV>
<DIV>- restart with "runsp" until convergence.</DIV>
<DIV> </DIV>
<DIV>or, run the AFM calculation with runsp only (i.e. with spins flipped but
without clmcopy)</DIV>
<DIV> </DIV>
<DIV>Antoine Villesuzanne<BR>ICMCB-CNRS<BR>87, Av. Dr. A. Schweitzer<BR>33608
Pessac Cedex<BR>Tél. 33 (0) 540008459<BR>Fax 33 (0) 540008373</DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=eric.sunyy@gmail.com href="mailto:eric.sunyy@gmail.com">Eric Sun</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=wien@zeus.theochem.tuwien.ac.at
href="mailto:wien@zeus.theochem.tuwien.ac.at">wien@zeus.theochem.tuwien.ac.at</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, August 31, 2005 6:12
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [Wien] About antiferromagnetism
calculation</DIV>
<DIV><BR></DIV>Dear WIEN2k users,<BR><BR>I'm trying to do some
antiferromagnetism calculations.<BR>I read the FAQ in the following page<BR><A
href="http://www.wien2k.at/reg_user/faq/afm.html">http://www.wien2k.at/reg_user/faq/afm.html</A><BR>I
realize that an important step in the AFM calculations <BR>is to manually flip
one of the spins of two adjacent<BR>magnetic atoms. My simple question is
that<BR>if this step is to avoid the so-called "local minimum"<BR>in the
variational procedure. I mean, if we just leave <BR>the two spins parallel,
will the variational procedure<BR>always stop at some ferromagnetic state? Or,
<BR>is it possible that, even if the spins are initially<BR>antiparallel, they
may ocassionally drop in <BR>the ferromagnetic "local minimum" in the
variational<BR>procedure?<BR><BR>Thanks for your kindly reply.<BR>Eric<BR>
<P>
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