Hi, Julen
Hi, Julen
Thank you for your immediate reply. I think you remarks are very usefully to me.
I have another question about the PBC in bulk calculation. Sometimes the
authors said, the PBC is used in their work, the supercell size (e.g. 4?4?4
supercell) is chosen so as to minimize the spurious effects of the repetition.
I wondering that what is meaning of 4, does it mean 4 primitive cells? And what
is the relationship between the supercell and the simulation box.
Thank you in advance.
Evan
-----????-----
???: "Julen Larrucea" <julenlist at gmail.com>
????: 2013?12?16? ???
???: "PWSCF Forum" <pw_forum at pwscf.org>
??:
??: Re: [Pw_forum] PBC problems
Dear Evan,
leaving distance between a molecule and the boundary is normally used only for
simulating isolated molecules, or surfaces (in order to simulate the vacuum on
one of the sides of the crystal).
The point in using PBC in bulk, is that you can simulate an infinite system by
only computing a few atoms, and therefore there should not be any gap at all.
A quick tip: you can use for example JMol for opening your pw.x output, and
then in the terminal type:
open "pw_output_file" {3 3 3}
This will show you 3 replicas of your system on each direction, and if you want
to simulate bulk, it should look uniform.
Best regards
Julen
On Mon, Dec 16, 2013 at 12:00 PM, ?? <maofei at mail.bnu.edu.cn> wrote:
Dear all
I have a general question about doing calculation with periodic boundary
condition (PBC). When I simulate the bulk materials (e.g. crystals), if I have
applied the PBC in 3 dimensions of the simulation box, do I have to give some
margins between the considered system and the boundary of the simulation box?
Or there should be no space between them, the system should connected with its
images seamlessly. But usually, as said in some papers, in order the minimize
the spurious interaction with its images, the distance between the considered
system and the boundary of the simulation box should be large enough.
I am a little puzzled with this issue. Any comment is appreciated. Thank you in
advance.
Evan
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Dr. Julen Larrucea
Postdoctoral researcher,
BCCMS, HMI Group, University of Bremen
Phone: +49 421 218 64582
Fax: +49 421 218 64599
http://www.larrucea.eu
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