[DFTB-Plus-User] Gold Fermi Energy

[Alessandro Pirrotta]

Thank you very much for your help.

Kind regards,
Alessandro

*Alessandro Pirrotta*
PhD student



*Faculty of Science*
Department of Chemistry &
Nano-Science Center
University of Copenhagen
Universitetsparken 5, C321
2100 Copenhagen Ø
Denmark

DIR +45 21 18 11 90
MOB +45 52 81 23 41

alessandro.pirrotta at chem.ku.dk

alessandro.pirrotta at gmail.com

www.ki.ku.dk

On 3 February 2015 at 16:43, Gabriele Penazzi <penazzi at uni-bremen.de> wrote:

>  Hi Alessandro,
>
> it's hard to give you a one-shot answer, for the following reason: in
> principle, a robust parameterization should give consistent results (i.e. a
> decent work function); in practice, as to do such a parameterization for
> gold is very challenging, there may be parameters out there tuned for one
> or another application but there's not any "official" Au parameter on
> dftb.org yet I can refer to. If your parameters have not been tested by
> someone else, you should do it yourself.
>
> I am assuming you are working with SCC, as the non-scc case is quite
> trivial. In SCC using the Fermi you get from your calculation should ensure
> that you converge to a bulk gold with zero charge transfer, and I would
> probably start from there. Then, whether for your particular case the band
> alignment can still be decent for your investigation, comparable with dft
> or even "better" for some lucky error cancellation, I cannot know it. I
> think anyway that a "wrong" (meaning not consistent with your lead
> calculation) Fermi level, if not too "wrong", will lead to charge
> compensation in the gold buffers and give a rigid energy shift, or at least
> this is what I saw in some systems. If this is the case, qualitative
> results should be robust with respect to your choice of Fermi level.
>
> Best,
> Gabriele
>
>
>
> On 02/03/2015 12:39 PM, Alessandro Pirrotta wrote:
>
> Dear Gabriele,
>
>  Thank you for your email. I have run the attached script and I get a
> gold Fermi energy of -2.9 eV.
> Do I want it to be close to the experimental value or do I take any value
> my parameters give me and use it for the transport calculation?
>  The input files are attached.
>
>  Kind regards,
> Alessandro
>
>   *Alessandro Pirrotta*
> PhD student
>
>
>
> *Faculty of Science*
> Department of Chemistry &
> Nano-Science Center
> University of Copenhagen
> Universitetsparken 5, C321
> 2100 Copenhagen Ø
> Denmark
>
> DIR +45 21 18 11 90
> MOB +45 52 81 23 41
>
>  alessandro.pirrotta at chem.ku.dk
>
> alessandro.pirrotta at gmail.com
>
> www.ki.ku.dk
>
> On 3 February 2015 at 10:09, Gabriele Penazzi <penazzi at uni-bremen.de>
> wrote:
>
>>  Hi Alessandro,
>>
>> you can calculate it with dftb itself, and be sure to be consistent with
>> your parameter set.
>> Anyway, if you have a "normal" junction with fermi level deep between
>> Homo-Lumo gap, I don't think it makes a huge difference besides an overall
>> shift, excess/defect charges should be compensated in the gold buffers. But
>> once you have one, be consistent.
>>
>> Best,
>> Gabriele
>>
>>
>> On 02/03/2015 09:37 AM, Alessandro Pirrotta wrote:
>>
>> Dear DFTB+ community,
>>
>>  I would like to ask you if there is a correct value for the Fermi
>> energy of gold.
>> I am running an electron transport calculation of molecular junction with
>> Au(111) and I am supposed to set the Fermi energy for the metal junction.
>> I have found different values such -4.8 eV, -5.1 eV and -5.53 eV and I do
>> not know on what basis I should pick one of them.
>>
>>  Kind regards,
>> Alessandro
>>
>>   *Alessandro Pirrotta*
>> PhD student
>>
>>
>>
>> *Faculty of Science*
>> Department of Chemistry &
>> Nano-Science Center
>> University of Copenhagen
>> Universitetsparken 5, C321
>> 2100 Copenhagen Ø
>> Denmark
>>
>> DIR +45 21 18 11 90 <%2B45%2021%2018%2011%2090>
>> MOB +45 52 81 23 41 <%2B45%2052%2081%2023%2041>
>>
>>  alessandro.pirrotta at chem.ku.dk
>>
>> alessandro.pirrotta at gmail.com
>>
>> www.ki.ku.dk
>>
>>
>> _______________________________________________
>> DFTB-Plus-User mailing listDFTB-Plus-User at mailman.zfn.uni-bremen.dehttps://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user
>>
>>
>> --
>> --
>> Dr. Gabriele Penazzi
>> BCCMS - University of Bremen
>> http://www.bccms.uni-bremen.de/http://sites.google.com/site/gabrielepenazzi/
>> phone: +49 (0) 421 218 62337
>> mobile: +49 (0) 151 19650383
>>
>>
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>>
>
>
> _______________________________________________
> DFTB-Plus-User mailing listDFTB-Plus-User at mailman.zfn.uni-bremen.dehttps://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user
>
>
> --
> --
> Dr. Gabriele Penazzi
> BCCMS - University of Bremen
> http://www.bccms.uni-bremen.de/http://sites.google.com/site/gabrielepenazzi/
> phone: +49 (0) 421 218 62337
> mobile: +49 (0) 151 19650383
>
>
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