Fermi energy not in midgap

[Matt W]

Hi,

can you define 'slight offset'? The Fermi level is determined numerically, 
so it is bound to not be precisely at the centre of the gap.

(Curiosity - should the Fermi level be precisely mid gap for a real 
material, or is the result just for simple 1D bands and no degeneracy?)

Matt



On Tuesday, August 1, 2017 at 5:48:45 PM UTC+1, ashish dabral wrote:
>
> Hi,
>
> I have calculated PDOS for semiconducting systems. While plotting dos I 
> realized that for the semiconductor, 
> the fermi energy is not lying in the midgap. No spin polarization is used. 
> I just take the fermi energy and 
> check if the mid of CB min. and VB maximum give me the fermi 
> energy(mid-gap). There is a slight offset towards
> conduction band. The system is definitely semiconducting. I can calculate 
> the fermi energy by taking mid value
> from CB and VB but why is fermi energy from cp2k  calculation is not 
> matching? Only Gamma point is used as
> the systems are large (100-200 atoms)
>
> Any pointers?
>
> Thanks
>
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