[DFTB-Plus-User] HOMO-LUMO gap in rectangular quantum dots

[SRKC Sharma Yamijala]

Dear all,

I have optimized a rectangular Graphene quantum dot in both SIESTA (PBE
functional) and DFTB+. I got the HOMO-LUMO gap to be ~ 0.5 eV using SIESTA
and ~ 0 eV using DFTB+ (even from the SIESTA optimized coordinates).

I have also tried with simple tight-binding code (only hopping considered)
with t=2.8 and I got the similar result as that of DFTB+ (~0 eV HOMO-LUMO
gap).

Is there a way, I can reproduce the SIESTA HOMO-LUMO gap using DFTB+?

Final coordinates and the input for DFTB+, SIESTA are attached.

geom.out.xyz is from DFTB+ and zgnr_C_8_308.xyz is from SIESTA.

Thanks,
Sincerely,
Sharma.


********************************************************
*Chaitanya Sharma,*
*Prof. Pati'*s group,
Chemistry and Physics Materials unit,
JNCASR, BANGLORE,
Lab:: (080-2208) 2581, 2809
https://sites.google.com/site/sharmasrkcyamijala/
*********************************************************
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