[DFTB-Plus-User] DFTB+ density of states against VASP density of states

[Bálint Aradi]

Dear Filippo.

it is easy to check, which one is the "correct" one. Just integrate up 
the DOS from the minimal energy up to the Fermi level. You should get 
the nr. of occupied states (provided each you have a 
semiconductor/insulator). If you try it for DFTB+, it gives exactly that 
(at least for the cases I've checked). What the norm for VASP is, I 
can't tell.

Cheers,

Bálint


On 24.05.22 02:30, Filippo Balzaretti wrote:
> Dear all,
> 
> I am comparing DFTB+ DOS with VASP DOS and, although the "shapes" are in 
> a good agreement, the DFTB+ one is way higher than that from VASP. This 
> doesn't depend on the system considered, but rather on the way both code 
> are computing the DOS. This is a problem in the moment one is interested 
> in comparing the areas, since any scaling of the curves would be 
> completely arbitrary.
> 
> My question is: why are the curves evaluated in DFTB+ much higher? What 
> is the best way to compare them and be sure that the integral is 
> representative of the number of electrons? Unfortunately I couldn't find 
> any documentation on this.
> 
> Here an original and scaled version of two DOS for you to understand 
> what I mean. The arbitrary scaling factor for the visual comparison was 
> chosen to let the maximum height of the DFTB curve be the same of that 
> of the DFT curve. The smearing used for both curves is the same 
> (Methfessel-Paxton, order 1, sigma = 0.2).
> 
> 
> 
> Thank you for helping me out!
> Best,
> Filippo Balzaretti
> 
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-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b-aradi/

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