If you used DFT method to obtain band structure than always remember a concept that DFT underestimate band gap, however it can provide trend in variation of band gap for different systems.
Abhishek Sharma On Fri, Mar 4, 2011 at 7:31 PM, Roberto Guerra <[email protected]> wrote: > Hello, > > I calculated the band structure of bulk amorphous silicon (64 atoms > tetrahedrically coordinated). I found an HOMO-LUMO band gap of about 0.7 > eV. > Then I performed the OpticalCalculation, but I have that the resulting > imaginary dielectric function has a peak at E<0.7. How is this possible? I > expect that each valence-to-conduction transition must be larger than the > bang-gap! > > Roberto >
