[DFTB-Plus-User] Regarding calculation of DOS

[u3129004 at edu.gifu-u.ac.jp]

Dear DFTB+ users,

I calculated density of states(DOS) for the system composed of graphene 
nanoribbon using DFTB+NEGF. I set Fermi level at the middle of bandgap 
and got a result(1).

When I stir this level(-0.05eV) for the same system, the result is 
greatly changed compared with result(1). Which result should I trust. 

In addition I have two questions.
First, around -4.2 eV there is a spike like noise. Why dose this one 
occur?

Second, I checked the unit of DOS, but I could not know it. What is the 
unit of DOS?

Thank you very much in advance,
Kazuma
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