[Wien] Need assistance

[Michael Sluydts]

Hello Mohammad,

For pure non-periodic clusters you may be able to try calculating 
optical properties in Gaussian. I'm not sure any kind of periodic code 
would be able to provide you with confinement, because confinement 
requires constrained dimensions which you are effectively removing by 
infinitely repeating your unit cell.

I am of course not sure whether you are studying colloidal quantum dots 
(nanocrystals) or the embedded kind in a semiconductor. I assume in 
theory you can represent some kind of quantum dot array in giant cells 
but once again it will become very heavy to calculate and I fear I'm not 
quite sure how you would get useful properties out of it. If you did 
that, maybe by studying the average potential variations throughout the 
cell you can study confinement, but I have no experience in this. If the 
confinement does not have to be 3-dimensional you can of course create 
an epitaxial structure in programs such as wien.

I myself use VASP and wien for my calculations but i only look at 
surface adsorption so I approximate them by infinite surfaces. Another 
program that may be useful for semi-periodic structures is Crystal09 
which seems to also be able to do 1D and 2D  structures, avoiding any 
artefacts you get from for instance repeating a surface slab in its 
surface direction.

You will most likely know best how your system looks like and what 
specific properties you need to extract useful data though.


Regards,

Michael Sluydts

Op 16/05/2013 10:38, Lawal Mohammed schreef:
> Hello Michael and Co,
> Can you please suggest any periodic code for quantum confinement 
> effect? And how can confinement and surface effects be neglected, in 
> such case what will be implication. please elaborate.
> With kind regards
> Mohammed
> ------------------------------------------------------------------------
> *From:* Michael Sluydts <Michael.Sluydts at UGent.be>
> *To:* A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
> *Sent:* Wednesday, May 15, 2013 3:49 PM
> *Subject:* Re: [Wien] Need assistance
>
> Hello Mohammad,
>
> It all depends what you want to do. Wien2k is optimal for calculating 
> properties of periodic structures, so it is mostly recommended for bulk.
>
> For confinement effects aperiodic code is recommended. However it is 
> unlikely you will ever be able to calculate optical properties of 
> anything larger than a small cluster aperiodically (extrapolation is 
> of course a useful tool).
>
> I myself do use periodic DFT to estimate surface adsorption on 
> colloidal quantum dots, so you'll have to pick the right tool for 
> whatever you are interested in.
>
>
> Regards,
>
> Michael Sluydts
>
>
> Op 15/05/2013 9:37, Lawal Mohammed schreef:
>> Dear Wien2k Community,
>> I am a new user of Wien2k code. I want to know if it is possible to 
>> do simulation study of quantum dots using Wien2k. Actually, I am 
>> about to start a research on quantum dots based materials for 
>> intermediate band solar cells. Therefore, I really need to know the 
>> potential of Wien2k package. Could you please help me?
>> With kind regards
>> Mohammed Lawal
>>
>>
>>
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>
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