Dear Gali Ádám:
I also found the 'routine' of 'GeometryConstraints' in the manual. But
it's too brief for me to use it. Would you mind send me some detail
information about this trick?
2007/3/27, [EMAIL PROTECTED] <[EMAIL PROTECTED]>:
Dear Yong Liu,
The symmetry is NOT included basically in SIESTA. In some simple cases you
can use some tricks in which you can still conserve the symmetry during
relaxation (using fixed fractional coordinates, etc).
In your case these tricks may not work. What you can still do is to use
the "constraints.f" file in SIESTA which can be activated within
GeometryConstraints block. By default, "constraints.f" file is a template
source and your calculation would not be affected. However, you can write
your specific constraints into this file using your specified atoms, etc,
which will conserve the symmetry what you want to achieve. You have to
compile the code again, and you will have such a code which will conserve
the symmetry for your particular(!) input.
This indeed works (with 1.3f version, for sure); for instance I could use
for studying the migration of a defect in a crystal constrained in a
chosen plane.
Yours,
Adam
> > I'd like to apply a restrict geometry optimization considering
the
> > symmetry of the system, but from the manual I do not find the useful
> > parameters. For instance, How can I fully optimize tetragonal PbTiO3
(P4mm,
> > No.99) which has a=b!=c, Pb(0,0,x1),
> > Ti(0.5,0.5,x2),O1(0,0.5,x3),O2(0.5,0,x3),O3(0.5,0.5,x4). I'm afraid
that
> > 'GeometryConstraints' is not good enough to deal with this work since
the
> > constrainsts of this parameter are not implemented, as mentioned in
the
> > manual.
> > Is there any parameters provide a mode of structural relaxtion
taking
> > into account the symmetry of the system and how to use them? Thanks a
lot in
> > advance.
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Dr. Gali Ádám Adam Gali, PhD
Budapesti Műszaki és Department of Atomic Physics,
Gazdaságtudományi Egyetem, Budapest University of Technology
and
Atomfizika Tanszék Economics
Budapest, Budafoki út 8., 1111 Budafoki út 8., H-1111, Budapest,
Hungary
telefon: 463-1580 telephone: [36]-(1)-463-1580
fax: 463-4357 fax: [36]-(1)-463-4357
e-mail: [EMAIL PROTECTED]
http://www.fat.bme.hu/homepages/galia/index.en.html
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--
Best regards.
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Liu, Yong, Ph D
Institute of Inorganic Materials,
Department of Materials Science and Engineering,
Zhejiang University,PR China
