[Wien] problem with B.S of InSb and InAs

[Peter Blaha]

You could use the "Engel-Vosko" GGA, which is option 25 instead of 13 in
case.in0

This GGA gives much better bandgaps and most likely will produce an
insulator. 
However, do NOT use this GGA for forces or Lattice parameter optimization,
since it will give very bad results.

> 
> > I have calculated the band structure , DOS and optical properties of
> > the semiconductors InP, InSb and InAs. The band structure for GaP is
> > ok, but for InAs and InSb show overlap around Gamma. that means it
> > show them as metallic. i know its wrong result because they are
> > semicounductords. So i asking how to solve this problem. Some one
> > told me it negative energy gap (the nagative sign means that there is
> > overlap around Gamma), is it so? please any one can explain to me
> > this... and what the solution..and the discussion for this case..
> 
> Band gaps are usually underestimated by LDA/GGA by 50-100%, and often
> metallic states are found for materials which are known to be
> semiconductors (many, many examples are discussed in the literature).
> There is no solution to this within LDA/GGA. For obtaining better
> optical properties, you might adjust the band gap to the experimental
> one by using the 'sciscors operator' in the input for the optical
> programs (see usersguide).
> 
> Stfaan
> 
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> 


                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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