[Wien] Reconstructed Si 100 surface
Michael Sluydts
michael.sluydts at ugent.be
Mon Jul 27 11:11:06 CEST 2015
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.sluydts at ugent.be <mailto:michael.sluydts at 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 <delamora at unam.mx
>> <mailto:delamora at 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-bounces at zeus.theochem.tuwien.ac.at
>> <mailto:wien-bounces at zeus.theochem.tuwien.ac.at>
>> <wien-bounces at zeus.theochem.tuwien.ac.at
>> <mailto:wien-bounces at zeus.theochem.tuwien.ac.at>> en nombre
>> de Muhammad Sajjad <sajjadpu at gmail.com
>> <mailto:sajjadpu at 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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