The ABINIT Users Mailing List ( CLOSED )

[Hua Bao <hbao@purdue.edu>]

Dear All,

I was trying the OPTIC function in ABINIT these days. For a first test, 
I changed GaAs in tutorial (toptic_3) to silicon. No luck, I got almost 
no absorption at the visible band (imaginary part of the dielectric 
function is at the 10E-4 order for 0 to 8 eV). Can anyone point out the 
problem for me?

Here is the input file.
ndtset 6

#First dataset : SC run with kpoints in the IBZ
  iscf1  3
 nband1  4   
 nstep1 100  
kptopt1 1
nbdbuf1 0
prtden1 1   getden1 0   getwfk1 0    ! Usual file handling data

#Second dataset : NSC run with large number of bands, and points in the IBZ
   iscf2 -2 
  nband2  9  ! Minimal number of bands for linear optics (imaginary 
part of the spectrum)
  nstep2 200
  nline2 15
 kptopt2  1
 getwfk2  1   getden2 1   ! Usual file handling data

#Third dataset : NSC run with large number of bands, and points in the 
the full BZ
   iscf3 -2 
  nband3  20  ! Minimal number of bands for linear optics (imaginary 
part of the spectrum)
  nstep3 200
  nline3 15
 kptopt3  2  ! Time-reversal symmetry can be used in the present 
implementation for linear optics
 getwfk3  2   getden3 1   ! Usual file handling data


#Fourth dataset : ddk response function along axis 1
  iscf4 -3
 nband4  20   ! Minimal number of bands for linear optics (imaginary 
part of the spectrum)
 nstep4  1  nline4  0
kptopt4  2   ! Time-reversal symmetry can be used in the present 
implementation for linear optics

  nqpt4  1  qpt4  0.0d0 0.0d0 0.0d0
 rfdir4  1 0 0
rfelfd4  2
getwfk4  3

#Fifth dataset : ddk response function along axis 2
  iscf5 -3
 nband5  20   ! Minimal number of bands for linear optics (imaginary 
part of the spectrum)
 nstep5  1  nline5  0
kptopt5  2   ! Time-reversal symmetry can be used in the present 
implementation for linear optics

  nqpt5  1  qpt5  0.0d0 0.0d0 0.0d0
 rfdir5  0 1 0
rfelfd5  2
getwfk5  3

Sixth dataset : ddk response function along axis 3
  iscf6 -3
 nband6  20   ! Minimal number of bands for linear optics (imaginary 
part of the spectrum)
 nstep6  1  nline6  0
kptopt6  2   ! Time-reversal symmetry can be used in the present 
implementation for linear optics

  nqpt6  1  qpt6  0.0d0 0.0d0 0.0d0
 rfdir6  0 0 1
rfelfd6  2
getwfk6  3


#Data common to all datasets
nshiftk 4
shiftk  0.5 0.5 0.5
        0.5 0.0 0.0
        0.0 0.5 0.0
        0.0 0.0 0.5
ngkpt  3*16        ! This is much too low : should be at least 24x24x24

acell   3*10.217
# amu 69.72  74.9216
diemac 10.0
ecut  8.00             ! This is also too low
# iscf 3
# ixc 3
natom  2  nbdbuf 2
ntypat  1
rprim   0 .5 .5  .5 0 .5  .5 .5 0
xred 3*0.00d0 3*0.25d0
# tnons 72*0.0
typat  1 1  tolwfr  1.e-16
znucl  14