[DFTB-Plus-User] NEGF_MPI: rare DOS results

[Marton]

Hi Matias,

Do you mean the high intensity spikes at energies ~-3.8 eV, -5.4 eV, -6 eV,
etc?

If yes -- I am not familiar with the NEGF code but I think it is actually a
good sign if you get those spikes (=Van Hove singularities) in the DOS of
nanotubes:

https://www.google.com/search?q=nanotube+dos&biw=1215&bih=915&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMIxaXTmpL8yAIVCjs-Ch2nLAXL

Cheers,
Marton Voros

--
Materials Science Division
Argonne National Laboratory

On Fri, Nov 6, 2015 at 9:18 AM, matias berdakin <matiasberdakin at gmail.com>
wrote:

> sorry I forgot to say bye in the last mail
>
> Thanks in advance
> Matias Berdakin
>
> 2015-11-06 10:18 GMT-03:00 matias berdakin <matiasberdakin at gmail.com>:
>
>> Hi everybody
>>
>> I'm doing my firsts trials with the DFTB+_NEGF_MPI (after the Tutorial
>> examples). I'm computing the DOS and the transmission function (non scc) of
>> a conducting carbon nanotube. At  first glance, the overall feature of the
>> DOS is what is expected for this system (see attached figure). Nevertheless
>>  the result present a series of symmetric spikes that make no sense.
>> I can not find the error in the calculation. So an idea is welcome.
>> At the end of the message I have pasted the geometry and the dftb_in.hsd
>> files.
>> [image: Imágenes integradas 1]
>> Geometry = GenFormat {
>> <<< 'coords_grande.gen'
>> }
>>
>> Transport {
>>   Device {
>>     AtomRange = 1 240
>>     FirstLayerAtoms =  1 121
>>   }
>>   Contact {
>>     Id = "source"
>>     AtomRange = 241 480
>>     FermiLevel [eV] = -4.602
>>     potential [eV] = 0.0
>>   }
>>   Contact {
>>     Id = "drain"
>>     AtomRange = 481 720
>>     FermiLevel [eV] = -4.602
>>     potential [eV] = 0.0
>>   }
>> }
>>
>> Hamiltonian = DFTB {
>>   SCC = No
>>   MaxAngularMomentum = {
>>     C = "p"
>>   }
>>
>>   SlaterKosterFiles = Type2FileNames {
>>     Prefix = "/mio-1-1/"
>>
>>     Separator = "-"
>>     Suffix = ".skf"
>>   }
>>
>> Eigensolver = GreensFunction {
>> ContourPoints = 50 50
>> }
>>
>> Analysis = {
>>     TunnelingAndDos {
>>       Verbosity = 101
>>       EnergyRange [eV] = -7.0 -3.0
>>       EnergyStep [eV] = 0.005
>>       Region = {
>>         Atoms = 1 240
>>       }
>>     }
>> }
>>
>>
>>
>
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