[Pw_forum] how to relax the atoms position without changing the cell parameters
Axel Kohlmeyer
akohlmey at cmm.chem.upenn.edu
Wed Jul 9 23:57:46 CEST 2008
On Thu, 10 Jul 2008, lan haiping wrote:
LH> Why not to read the Document and related INPUT ?
please read e-mails a little bit more carefully
before responding and giving potentially incorrect
advice. it mentions a simple cubic crystal with
a benzene molecule on each position, so it is
not about a simple molecule optimization.
the problem for these systems is actually, that
with DFT you get too _little_ interaction between
the benzene molecules (except at high pressure,
of course) due to the incomplete description of
dispersion interactions...
cheers,
axel.
LH> If you just want to do a simple relaxation for a molecule , two
LH> points
LH> should be
LH> taken into attention :
LH> 1, The cell should be large enough to avoid image intetactions.
LH> 2, gamma sampling for BZ
LH> P.S , please supply your affiliation
On Wed, Jul 9, 2008 at 11:52 PM, ËïÑô <sunyang198498 at gmail.com> wrote:
> Hi!
> how could I relax the atoms position without changing the cell parameters
> say, if i have a simple cubic cell with each point having a benzene
> structure. How could I relax the benzene's atoms, say, hydrogen and
> carbon with the fixed edge size within the simple cubic cell.
>
> Thank you,
>
> Yang
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--
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping at gmail.com, hplan at pku.edu.cn
--
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Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu http://www.cmm.upenn.edu
Center for Molecular Modeling -- University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582, fax: 1-215-573-6233, office-tel: 1-215-898-5425
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