[Pw_forum] can one do hybrid calculations with smearing

[Rajdeep Banerjee]

Dear all,
           I was calculating band gap with hybrid functionals for a
semiconductor. If I don't use smearing (i.e. occupations = 'fixed') the
dos  seems ok but whenever I use smearing and plot dos, at some energies I
get negative density of states ! I can't understand why this is happening.
Can/should one use smearing for hybrid functionals? Following is the
important part of the input:

 &system
    ibrav = 4,
    celldm(1) = 6.474424, celldm(3) = 5.837554613 ,
    nat = 10, ntyp = 3,
    ecutwfc = 40,
    london = .true.,
    nbnd = 25,
    occupations = 'smearing', smearing = 'mv', degauss = 0.001,
    input_dft = 'hse',
    exxdiv_treatment = 'gygi-baldereschi',
    x_gamma_extrapolation = .true.,
    nqx1 = 4, nqx2 = 4, nqx3 = 1

...

    Another problem is that whenever I use smearing the output doesn't give
HOMO-LUMO as it considers it as metal and prints only the fermi energy. So
if I'm studying semiconductor to metal transition there's no way one can
check the band gap change.

    I'd be greatful if anyone can shine some light on above problems.

Thnaks,
Rajdeep Banerjee
Ph. D. student
JNCASR
Bangalore, India
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