It is recommended to make both your slab surfaces identical where
possible. The p21, p22 and p24 refer to the type of supercell used to
represent the surface. Since you are using a periodic model you are
imposing a strong symmetry on the surface, not all reconstructions can
be made within your unit cell, indeed for your dimer you will need a 2x1
expansion, i.e. two cells next to eachother along the a axis. The
symbols (and possible angles) represent the shape and rotation of the
resulting cell (in this case p=primitive, c=centered).
You can find more info in for instance:
Introduction to Solid State Physics - Kittel - about the description of
cells
and
Density Functional Theory: A Practical Introduction - Sholl and Steckel
- for the basics of how to model surfaces
Muhammad Sajjad schreef op 27/07/2015 om 10:51:
Dear Delamora and Michael
Many thanks for informative suggestions.
I am intended to study electronic properties of Si (100) of thickness
1 nm. I am asked to introduce dimers instead of using H. But my
question is "one surface of the Si 100 must be passivated by hydrogen
or not?"Like If ones introduce dimer on the top (maximum Z) then
bottom (minimum Z) must be passivated or not? Can we introduce dimers
on both surfaces (top & bottom). I am reading the paper (
http://pubs.acs.org/doi/pdf/10.1021/jp509095t ). What does it means
P21, P22, P24 reconstructions?
Many thanks
On Sun, Jul 26, 2015 at 10:51 PM, Michael Sluydts
<michael.sluy...@ugent.be <mailto:michael.sluy...@ugent.be>> wrote:
Muhammad,
When you move the two Si atoms with the dangling bond towards
eachother you will create a dimer on the surface, no extra
passivation by H atoms is needed, just ensure you make your slab
symmetric where possible. If you google Si recontructions you
should find very exact geometrical information since this has been
done many times before.
Best regards,
Michael Sluydts
Muhammad Sajjad schreef op 26/07/2015 om 17:59:
Thank you Pablo
But I am required to connect two Si atoms at the surface to
reduce one dangling bond and then put H or may be H is not needed
if both of the dangling bonds have possibility of omitting. I am
reading the paper but could not understand although Fig. 2 is
looking easy to understand. WHat is 2*1 or 2*2 or 2*4 ? are the
super-cells like 2*1*1 or 2*2*1 etc.
On Sun, Jul 26, 2015 at 6:22 PM, delamora <delam...@unam.mx
<mailto:delam...@unam.mx>> wrote:
This is the same that I simplified and symmetized. If you are
going to add H then you need set the space group as P1 (#1)
so the H can move freely and not in a symmetrical path.
Now, if you use my proposed structure then you can put
inversion (SG P-1, #2) and add two H, one on each surface,
but in a symmetric way.
Other thing, maybe my proposed structure is too small and
your structure is ok, but I would symmetrize as I explained
in an earlier message.
Pablo
------------------------------------------------------------------------
*De:* wien-boun...@zeus.theochem.tuwien.ac.at
<mailto:wien-boun...@zeus.theochem.tuwien.ac.at>
<wien-boun...@zeus.theochem.tuwien.ac.at
<mailto:wien-boun...@zeus.theochem.tuwien.ac.at>> en nombre
de Muhammad Sajjad <sajja...@gmail.com
<mailto:sajja...@gmail.com>>
*Enviado:* domingo, 26 de julio de 2015 04:44 a. m.
*Para:* wien
*Asunto:* [Wien] Reconstructed Si 100 surface
Dear Users
Kindly guide me how to reconstruct Si 100 layer? The Si 100
structure is attached here with. It has two dangling bonds on
both surfaces (Top and Bottom). My intension is to keep one
dangling bond on the top and bottom surfaces that will be
saturated by H addition.
--
Kind Regards
Muhammad Sajjad
Post Doctoral Fellow
KAUST, KSA.
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--
Kind Regards
Muhammad Sajjad
Post Doctoral Fellow
KAUST, KSA.
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--
ir. Michael Sluydts
Center for Molecular Modeling
Ghent University
Technologiepark 903
9052 Zwijnaarde, Belgium
tel. +32 (0)9 264 66 19
https://molmod.ugent.be
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--
Kind Regards
Muhammad Sajjad
Post Doctoral Fellow
KAUST, KSA.
_______________________________________________
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--
ir. Michael Sluydts
Center for Molecular Modeling
Ghent University
Technologiepark 903
9052 Zwijnaarde, Belgium
tel. +32 (0)9 264 66 19
https://molmod.ugent.be
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