[DFTB-Plus-User] Band gap of graphene

[SRKC Sharma Yamijala]

Dear all,

Band gap problme is solved (I have been interpreting the results in a wrong
manner for the last few days [I was plotting with wrong Fermi-energy
value]. Kindly, excuse me in this regard.), but I need to know whether the
SCC convergence is going correctly or not. Every "Geometry step" is getting
completed by running only one SCC iteration. In manual example it is not
so. Kindly, help me.

The last few lines of the output of my system are as below:


********************************************************************************
** Geometry step: 25, Lattice step: 10
********************************************************************************

  iSCC Total electronic   Diff electronic      SCC error
    1   -0.55899164E+02    0.00000000E+00    0.20237145E-11

 Total Energy:                     -54.9846405060 H
 Total Mermin free energy:         -54.9846405060 H
 Volume:                             0.171654E+05 au^3
 Pressure:                           0.854991E-09 au     0.251547E+05 Pa
 Maximal force component:            0.600174E-05
 Maximal Lattice force component:    0.244084E-04 au
>> Charges saved for restart in charges.bin

********************************************************************************
** Geometry step: 26, Lattice step: 10
********************************************************************************

  iSCC Total electronic   Diff electronic      SCC error
    1   -0.55899164E+02    0.00000000E+00    0.20237145E-11

 Total Energy:                     -54.9846405060 H
 Total Mermin free energy:         -54.9846405060 H
 Volume:                             0.171654E+05 au^3
 Pressure:                           0.854991E-09 au     0.251547E+05 Pa
 Maximal force component:            0.600174E-05
 Maximal Lattice force component:    0.244084E-04 au
>> Charges saved for restart in charges.bin

 Geometry converged


Sincerely,
Sharma.








********************************************************
*Chaitanya Sharma,*
*Prof. Pati'*s group,
Chemistry and Physics Materials unit,
JNCASR, BANGLORE,
Lab:: (080-2208) 2581, 2809
https://sites.google.com/site/sharmasrkcyamijala/
*********************************************************


On Tue, Jul 8, 2014 at 7:56 PM, SRKC Sharma Yamijala <sharmajncasr at gmail.com
> wrote:

> Dear DFTB+ community members,
>
> Following the DFTB+ manual and recipes, I set up the optimization
> calculation for graphene. When I have plotted the DOS, instead of attaining
> a zero-band-gap semiconductor, I found an insulator with ~3 eV gap. I have
> tried with both mio and 3ob SKF files. I have attached the input and DOS
> for the reference.
>
> It would be a great help for me if any one of you can point out the
> mistake.
>
> I have seen many papers using DFTB+ to study Graphene/G-NRs/G-QDs. So, I
> hope at least somebody can provide their input file and the corresponding
> SKF files to help me to start a new project.
>
> Thanking you for your support,
> Sincerely,
> Chaitanya Sharma.
>
> P. S.: I have already seen all the threads starting from 2007 to 2014 (and
> I have been following the forum from the last 2 months) and I couldn't find
> a problem of this kind (except one and which is unanswered). From recent
> threads I found that,* Dr. Anusha and Dr. Bálint Aradi* are discussing on
> GNRs, so I request them to help me in this regard, if they can.
>
>
>
>
>
>
>
> ********************************************************
> *Chaitanya Sharma,*
> *Prof. Pati'*s group,
> Chemistry and Physics Materials unit,
> JNCASR, BANGLORE,
> Lab:: (080-2208) 2581, 2809
> https://sites.google.com/site/sharmasrkcyamijala/
> *********************************************************
>
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