[Wien] (no subject)

[Peter Blaha]

An optical band gap is usually a direct band gap (You can't change the 
momentum of the electron by photons, only if they are coupled to phonons 
too).

The "experimental" gap can be both, the fundamental (maybe indirect) or 
the optical gap, this depends if the "experimental gap" was measured 
optically or by photoemission/inverse PE.


On 01/29/2015 02:11 PM, Dr. K. C. Bhamu wrote:
> Dear Wien2k User
> I am still waiting for my question.
>
> The question is that "If a compound shows two band gaps, direct and
> indirect then which one should be compared with optical/experimental
> band gap?"
>
> regards
>
> *Bhamu*
> **
>
> On Fri, Jan 9, 2015 at 10:56 AM, Dr. K. C. Bhamu <kcbhamu85 at gmail.com
> <mailto:kcbhamu85 at gmail.com>> wrote:
>
>     Dear Wien2k Users
>
>     Optical band gap of a ternary compound is 3.5eV and by theoretical
>     calculations its showing two band gaps direct and indirect around
>     2.1 and 3.2 eV, respectively.
>
>     Which band gap I should use to compare with optical value?
>
>
>     regards
>
>     Bhamu
>
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-- 

                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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