[Wien] Energy gap zero in outputtrance file of Boltztrap calculation

[Gavin Abo]

You might try increasing lpfac [ 
http://cms.mpi.univie.ac.at/vasp-forum/viewtopic.php?f=4&t=9660&p=14325#p14325 
].

On 12/14/2015 10:48 PM, saurabh singh wrote:
> Dear Wien2k users,
>
> I am using wien2k 14.2 version. I performed the LDA+U calculation 
> (runsp_lapw -orb -cc 0.0001)  for the ZnV2O4 compound (using 
> tetragonal  Antiferromagnetic structure file) with k point 40X40X40. I 
> obtained the required energy and charge convergence criteria. In the 
> case.scf file the value of fermi energy is 0.4903644 Ry. In the 
> case.scf file and the total DOS calculation it shows there is energy 
> gap of 0.330 eV (i.e. .0242 Ry) about the fermi energy.  Using the 
> case.energyup/dn file I calculated the transport properties using 
> Boltztrap code (x_trans BoltzTraP -up -orb). The intrans file used for 
> the calculation is as follows:
>
> WIEN                                       # Format of DOS. Either 
> WIEN for to use WIEN like case.struct and case.energ
> 1 0 0 0                                     # isetfermi idebug setgap 
> gapchange
> 0.49036  0.0005 0.4 136.0000    # Fermilevel (Ry), deltae, ecut, 
> number of valence electrons
> CALC                                       # CALC (calculate expansion 
> coeff, Eq.(p1), NOCALC (read from file)
> 5                                            # lpfac, number of 
> latt-points per k-point
> BOLTZ                                    # run mode (only BOLTZ is 
> supported)
> 0.15                                        # efcut. energy range of 
> chemical potential around efermi that is used
> 1400. 20.                                 # Tmax, temperature grid
> -1.0                                        # Energyrange of bands 
> given individual DOS output sig xxx
> TETRA                                  # scheme to obtain DOS. 
> HISTO/TETRA: histogram/thetrahedron[4] sampling
> #0 0 0 0 0                              # τ -model. Not documented
> #2                                         # number of fixed dopings
> #1E20 -1E20                         # fixed doping levels in cm−3
>
>
> after the boltztrap calculation there is no gap obtained in 
> case.outputtrans file. If I used the value of Fermienergy a bit more 
> in the intrans file which lies in the band gap as observed in DOS 
> plot, still we don't get any gap in the case.outputtrans file. May I 
> know the reason why we are unable to get the gap in outputtrans file. 
> The below outputtrans file is correspond to the fermienergy 0.49036, 
> 0.49536 and 0.502100 Ry
>
> 1.
> ==============  OUTPUT from BANDANA       ================
> Egap:     0.000000 Energy range:     0.037447 -     0.944497. Bands 
> range:   89 -  172
> VBM:     0.490360 CBM:     0.490360 Efermi:     0.490360
>
> 2.
>
> ==============  OUTPUT from BANDANA       ================
> Egap:     0.000000 Energy range:     0.037447 -     0.944497. Bands 
> range:   89 -  172
> VBM:     0.495360 CBM:     0.495360 Efermi:     0.495360
> -
>
>
> 3.
> ==============  OUTPUT from BANDANA       ================
> Egap:     0.000000 Energy range:     0.037447 -     0.944497. Bands 
> range:   89 -  172
> VBM:     0.502100 CBM:     0.502100 Efermi:     0.502100