The ABINIT Users Mailing List ( CLOSED )

[Fabien Bruneval <fabien.bruneval@polytechnique.fr>]

Hi Ariesto,

If you are interested in calculating reliable band structures, you may
consider to use the GW approximation (implemented in abinit). GW is a
correct way, in theory and in practice, to evaluate the electronic band
structure. It corrects for the underestimation of the band gap of DFT
and may also change the shape of the bands.

For instance, in M. van Schilfgaarde et al. PRL 96 226402 (2006) (Fig.
2), the authors show that the effective mass of the first conduction
band of GaAs is much better within GW (and self-consistent GW) than
within LDA. Therefore, the curvature of the LDA band structure may be
always correct...

Hope I have convinced you to enter the small family of the GW users.


Fabien



Anglade Pierre-Matthieu wrote:
> Hi all,
> 
> For as much as I know, Band structures are known to have almost
> correct shapes but with large discrepancies in term of band gap.
> Ariesto find that the shape is also not correct does anyone knows
> about that ?
> 
> It happens that some people shift only there computed band structure
> to reach experimental band gap without much other changes. So I guess
> that you should usually find almost correct shape for your valence
> band.
> 
> regards
> 
> PMA
> 
> 
> 
> On 3/1/07, 아리에스토 <ariesto@postech.ac.kr> wrote:
> 
>>
>>
>>
>> Dear DR.Pierre-Matthieu Anglade,
>>
>>
>>
>> Sorry for sending question personaly, because my  email to forum was 
>> rejected again as before,although I login  properly
>>
>>
>>
>>
>>
>> I have aquestion,
>>
>> It is already  mentioned in tutorial 3.5 that DFT calculation produces 
>> underestimate value of  bandgap.
>>
>> I also found ,after figuring out t35.out file, the fermi Energi  is 
>> not in the midle of band gap. the fermi energy is located below the 
>> top of  valence band in Gamma point.
>>
>> Now, in graphene system , I also found the  same thing.
>>
>> Is the problem also well known as band strucutre DFT  problem?
>>
>> Best regards,
>> Ariesto
>>
>>
>>
>>
>>
>>
>>
>>
> 
> 
>