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[Xavier Gonze <gonze@pcpm.ucl.ac.be>]

Dear Hartwin,

Just a technical point : you might decrease by much your ecut
if you were using non-zero ecutsm (typically 0.5Ha).
Indeed, like the total energy as a function of
the cell size, the eigenenergies are affected by abrupt changes
of the number of planewaves due to the cut-off energy.

A question : do you get the same (wrong) mass without spin-orbit ?

Finally, you might have to try GW ...

Regards,
Xavier

On 21 Nov 2005, at 14:46, Vincenzo Fiorentini wrote:

> also, well, m* kind of depends on pseudo properties,
> so getting it right may be to some extent a matter of
> luck.
>
> 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