[Wien] gap

[Rocquefelte]

  Band gap is always a matter of what quantity you are looking for: 
electronic conductivity, optical propeties ...

In the present case the band gap obtained in the band structure is the 
fundamental band gap (direct or indirect).
The band gap given by the DOS is certainly smaller, because you do not 
have the information related to the energy dispersion of the bands.

You should also do the difference between the optical band gap and the 
fundamental band gap for instance.

So what is the right value? From a theoretical point of view the right 
value (the more accurate) is the fundamental band gap. However, you must 
think about the fact that a band gap is a useful quantity if it is 
related to a property!
If you are looking to optical properties, the best value will be 
obtained from the dielectric function.
If you are looking at electronic properties ... band structure is 
well-suited ...

Regards

Xavier


Le 17/10/2012 17:26, ben amara imen a écrit :
> Hello !
>
>  I want to determine the gap's value for my compound. So, I have 
> calculated DOS and structure bands SB. In my case, DOS gives a value , 
> SB gives me  another different value and I have found a another value 
> in case.SCf2 . So I have a three different value of gap !!!!
>
> I want to know the singnification of each value (given by DOS; SB and 
> case.SC2 ) and what's the right value??? I mean what the right value 
>  that I have to choose
>
> Can someone helps me please!
>  And thanks in advance
>
>
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