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[文沈 <wshen02@gmail.com>]

I think I've changed to the hexagonal structure and also changed the occopt=3 to show it is metallic,
Any problems still there? 
My file for the calculation for graphite is as follows,any suggestion or correction is welcomed!

  ndtset 6

#First dataset : SC run with kpoints in the IBZ
   iscf1  3
  nband1  20     
  nstep1 25   
 kptopt1 1
 nbdbuf1 0
 prtden1 1   getden1 0   getwfk1 0    ! Usual file handling data

#Second dataset : NSC run with large number of bands, and points in the IBZ
    iscf2 -2  
   nband2 20  ! This number of bands might be too low for non-linear optics and real part of linear optics
   nstep2 25
  kptopt2  1
  getwfk2  1   getden2 1   ! Usual file handling data

#Third dataset : NSC run with large number of bands, and points in the the full BZ
    iscf3 -2  
   nband3 20  ! This number of bands might be too low for non-linear optics and real part of linear optics 
   nstep3 25
  kptopt3  3
  getwfk3  2   getden3 1   ! Usual file handling data


#Fourth dataset : ddk response function along axis 1
   iscf4 -3
  nband4 20   ! This number of bands might be too low for non-linear optics and real part of linear optics
  nstep4  1  nline4  0
 kptopt4  3

   nqpt4  1  qpt4  0.0d0 0.0d0 0.0d0 
  rfdir4  1 0 0
 rfelfd4  2
 getwfk4  3

#Fifth dataset : ddk response function along axis 2
   iscf5 -3
  nband5 20   ! This number of bands might be too low for non-linear optics and real part of linear optics
  nstep5  1  nline5  0
 kptopt5  3

   nqpt5  1  qpt5  0.0d0 0.0d0 0.0d0
  rfdir5  0 1 0
 rfelfd5  2
 getwfk5  3

 Sixth dataset : ddk response function along axis 3
   iscf6 -3
  nband6 20   ! This number of bands might be too low for non-linear optics and real part of linear optics
  nstep6  1  nline6  0
 kptopt6  3

   nqpt6  1  qpt6  0.0d0 0.0d0 0.0d0
  rfdir6  0 0 1
 rfelfd6  2
 getwfk6  3


#Data common to all datasets
 nshiftk 1
 shiftk  0.0 0.0 0.5
 ngkpt 9 9 9      ! This is much too low : should be at least 24x24x24

 amu    12 
 diemac 9.0
 ecut 10.00             ! This is also too low
 iscf 3
 ixc 3
 natom  4 nbdbuf 2
 ntypat  1
acell 4.651 4.651 12.67611         
rprim  0.86602540378  -0.5   0.0
       0.86602540378  0.5   0.0
       0              0    1
 xred  0 0 0
       1/3 1/3 1
       2/3 2/3 0.5
       1/3 1/3 0.5
       
 tnons 72*0.0
 typat  1 1 1 1  tolwfr  1.e-20
 znucl  6

occopt=3

On Tue, Mar 10, 2009 at 9:05 AM, 文沈 <wshen02@gmail.com> wrote:

I changed my shiftk as follows
 nshiftk 1
 shiftk  0.0 0.0 0.5
ngkpt 8 8 8
I know the number of ngkpt is not enough, but I think at least it should give some graph which have the more or less the same peaks, right?
Besides, how can I treat that as metallic system? what should I change except diemac?

Thanks a lot,. guys!

Wen

On Tue, Mar 10, 2009 at 1:55 AM, matthieu verstraete <matthieu.jean.verstraete@gmail.com> wrote:

your kpoints are completely inappropriate:
1) you need a much finer mesh for graph*, especially for dielectric response
2) the shiftk you use are for an fcc structure, not hexagonal. Please read the appropriate tutorials (3+4) carefully.
3) as PMA mentioned, for graphene (an almost metal) and graphite (because its gap is ridiculously small) you should be treating the system as metallic and including the K point in the samplint (3n x 3n mesh of kpoints). This last point is less crucial once you converge the mesh properly.

Matthieu

On Tue, Mar 10, 2009 at 8:14 AM, Anglade Pierre-Matthieu <anglade@gmail.com> wrote:

First, I've never done any optic calculation. So I'm not a specialist.
Now : The dielectric function is the response of your material to an
electric field. You know that metals and semiconductors have very
different response to this. Then if one considers only the k-point
where there is a gap in graphen I would expect a noticeable effect on
the dielectric function.

regards

PMA

On Mon, Mar 9, 2009 at 11:34 PM, 文沈 <wshen02@gmail.com> wrote:
> Does this point matter a lot? I am just using the normal sampling as follows
> nshiftk 4
>  shiftk  0.5 0.5 0.5
>          0.5 0.0 0.0
>          0.0 0.5 0.0
>          0.0 0.0 0.5
>  ngkpt 4 4 4
> could you tell me why the sampling of the k point will have a effect on the
> calculation result?
>
> yours
> Wen
>
> On Mon, Mar 9, 2009 at 12:52 PM, Anglade Pierre-Matthieu <anglade@gmail.com>
> wrote:
>>
>> Does your reciprocal space sampling include the point where conduction
>> bands crosses the valence bands ?
>>
>> On Mon, Mar 9, 2009 at 6:46 PM, 文沈 <wshen02@gmail.com> wrote:
>> > Dear Abinit users,
>> > I am currently using abinit to calculate the dielectric function of
>> > graphite
>> > and graphene. But the problem is whatever pseudopotential I use, I get
>> > very
>> > bad result which I mean I get nearly all 0 for the imaginary part. I've
>> > already made sure that my structures are right.
>> >
>> > So anybody who calculate the dielectric function for Carbon please give
>> > me
>> > some idea what is the problem.
>> > Thanks a lot !
>> >
>> > Yours
>> > Wen
>> >
>>
>>
>>
>> --
>> Pierre-Matthieu Anglade
>>
>
>

--
Pierre-Matthieu Anglade

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Matthieu Verstraete

European Theoretical Spectroscopy Facility (ETSF) 
Dpto. Fisica de Materiales, 
U. del Pais Vasco,            
Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
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Mail : matthieu.jean.verstraete@gmail.com
http://www-users.york.ac.uk/~mjv500