[Pw_forum] Temperature effect on band gap

Lorenzo Paulatto lorenzo.paulatto at impmc.upmc.fr
Thu Sep 24 09:59:39 CEST 2015

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
23-24/4é16 Boîte courrier 115
4 place Jussieu 75252 Paris Cédex 05

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