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[Vincenzo Fiorentini <vincenzo.fiorentini@dsf.unica.it>]

I notice you have 10.61 as lattice constant. is that
your theoretical value ? presumably you should be using
a_theo. m* is very strongly dependent on volume. best,
Vincenzo

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vincenzo.fiorentini@dsf.unica.it
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On 21 Nov 2005, at 2:31 PM, Peelaers Hartwin wrote:

> Dear Abinitioners,
>
>
> I'm trying to calculate the effective bandmass of GaAs. To do that I'm
> fitting a 4th order polynomial expressing the energy as function of  
> k around
> the gamma point. (Before that I also rescaled the reduced  
> coordinates of the
> k-points using the values of the reciprocal unit vectors.) The  
> effective
> bandmass is then the reverse of two times the coefficient in front  
> of k^2.
> This procedure works well for Si (where I fitted the energy around the
> minimum in the conduction band close to the X point), but not for  
> GaAs,
> where I obtain a value of 0.019 (0.021 when the odd powers of k are  
> forced
> to be zero). Earlier ab initio investigations (PRB 46, 2086(1992))  
> obtained
> the correct value of 0.064.
> Attached you will find my input file. This input file uses hgh
> pseudopotentials (including 3d electrons). I also tried other
> pseudopotentials with very similar results. To improve accuracy of the
> outputted values I changed the abinit source files to output more  
> digits.
> Does anybody see what I am doing wrong? Can someone give a  
> suggestion on how
> to improve my results?
>
> Best Regards,
>
> Hartwin Peelaers
>
>
>
> ---------------------------------------------
> University of Antwerp - Department of Physics
> CMT - U208
> Groenenborgerlaan 171
> B-2020 Antwerp
> Belgium
>
>
>
> # Crystalline GaAs
> #Set 1 : ground state self-consistency
> ndtset 2
> ecut   170
> kptopt   1
> toldfe   1.0d-9
> prtden1 1
> nband1 30
> pspso 2 2
> nspinor 2
> prtvol 2
>
> #Definition of the unit cell
>     acell   3*10.61
>     rprim   0.0  0.5  0.5
>             0.5  0.0  0.5
>             0.5  0.5  0.0
>
> #Definition of the atom types
>    ntypat   2
>     znucl   31 33
>
> #Definition of the atoms
>     natom   2
>     typat   1 2
>
>      xred   0.0  0.0  0.0
>             0.25 0.25 0.25
>
> #Definition of the k-point grid
>
> ngkpt  4 4 4
>
> nshiftk   4
>  shiftk   0.0 0.0 0.5
>           0.0 0.5 0.0
>           0.5 0.0 0.0
>           0.5 0.5 0.5
>
> #Set 2
> iscf2    -2
> getden2  -1
> kptopt2  -1
> nband2   30
> ndivk2   100
> kptbounds2 0 -0.01 -0.01  #along delta-line
>            0   0     0
> tolwfr2  1.0d-12
>
> #Definition of the SCF procedure
>      iscf   5
>     nstep   25
>    diemac   9.0