[DFTB-Plus-User] Fermi energy at DFTB+

[Robyn.Shi at csiro.au]

Hi Guys,

does anyone know how DFTB+ calculates the value of the Fermi energy given in "detailed.out"? and WHY does DFTB+ deals with the Fermi energy in this way? I found the Fermi energy given at "detailed.out" does not exactly sit in the middle of HOMO and LUMO for the semi-conductor-like systems from molecular sizes to cluster sizes and to the periodic one. Actually the Fermi energy given by DFTB+ is closer to HOMO in my systems.

One things I cannot understand in the Fermi energy provided by DFTB+ is that the Fermi energy does not converge CONTINUALLY when the size of the systems increases. Although the Fermi energy converges to the periodic one, there is a jump (~ 0.5 eV in my systems) existing during the converging process. Does anyone have any ideas to explain the jump?

Thanks.

Best regards,

Robyn
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