[Pw_forum] Carrier concentration in Si

Lorenzo Paulatto lorenzo.paulatto at impmc.upmc.fr
Tue Sep 15 15:12:40 CEST 2015

deal Galvin,
I think that you can assume that band structure does not depend on 
temperature. Furthermore, a realistic temperature corresponds to a Fermi-Dirac 
smearing temperature which is very small. I.e. 300K correspond to just 2 mRy. 
It would take a huge amount of k-points to converge such a calculation.

It would be better to do the calculation without smearing, with just a few 
extra bands, compute a very fine density of states, then compute the 
occupations directly in the energy domain. 

But in the end, what you're going to get is just the integral the FD 
distribution, centered on the Fermi energy, from the LUMO up to infinity, 
which you can do analytically and depends only on the band gap.

kind regards

On Tuesday, September 15, 2015 10:57:27 AM Khara, Galvin wrote:
> Hey,
> I was wondering if there was a (relatively) straightforward way of
> calculating the carrier concentration of a system using quantum espresso? I
> want to apply an electronic temperature using fermi-dirac smearing, and
> calculate the carrier concentration for Silicon at various electronic
> temperatures.
> Thanks,
> Galvin

Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
+33 (0)1 44 275 084 / skype: paulatz
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