[Pw_forum] Temperature effect on band gap

[reza vatan]

Dear Lorenzo,

Thanks for your comment. I tried changing the lattice constants effect band
gap, but I got reverse trend which was increasing the band gap by
increasing lattice constants. In experiment, people measure smaller band
gap in higher temperature (larger lattice constant). By any chance, do you
know where the problem is?

Best,
Reza

On Thu, Sep 24, 2015 at 12:59 AM, Lorenzo Paulatto <
lorenzo.paulatto at impmc.upmc.fr> wrote:

> On Wednesday, September 23, 2015 01:07:34 PM reza vatan wrote:
> > I'm trying to use QE to see the effect of temperature on the band gap of
> a
> > material. So I just wanted to if there is any way to include the
> > temperature in electronic structure calculations using QE.
>
> Dear Reza,
> with some possible exception in extreme cases, the gap does not depend on
> the
> "electronic" temperature, even a high temperature correspond to a smearing
> of
> the Fermi-Dirac occupation which is much smaller than what we normally use
> to
> ease convergence in metallic systems.
>
> On the other hand, the band gap can depend on the temperature via the
> lattice
> expansion. To have a rough idea, apply the experimental lattice expansion
> to
> the zero-temperature DFT lattice, repeat the scf and bands calculation,
> check
> how the band structure changes.
>
> kind regards
>
>
> --
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS & Université Paris 6
> +33 (0)1 44 275 084 / skype: paulatz
> http://www.impmc.upmc.fr/~paulatto/
> 23-24/4é16 Boîte courrier 115
> 4 place Jussieu 75252 Paris Cédex 05
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20150924/3d043fd3/attachment.html>