ABINIT Discussion Forums

Hello,
I got an problem about the optic calculations with abinit and the 'optic' tool. I calculated the imaginary spectrum and Reflectance spectrum of Al. It was not smooth enough with several peaks as could be seen in the picture. The reflectivity calculated differs insufferably from the values measured experimently. Can you have a look at my input file and tell me if any variable is not set reasonable? Your favorable assistance will be highly appreciated.



ndtset 6

#First dataset : SC run with kpoints in the IBZ
iscf1 3
nband1 3 !
nstep1 1000
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 60 !!!!!! This number of bands might be too low for non-linear optics and real part of linear optics
nstep2 1000
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 60 !!!!!! This number of bands might be too low for non-linear optics and real part of linear optics
nstep3 1000
kptopt3 1
getwfk3 2 getden3 1 ! Usual file handling data


#Fourth dataset : ddk response function along axis 1
iscf4 -3
nband4 60 !!!!!! This number of bands might be too low for non-linear optics and real part of linear optics
nstep4 1 nline4 0
kptopt4 1

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 60 !!!!!! This number of bands might be too low for non-linear optics and real part of linear optics
nstep5 1 nline5 0
kptopt5 1

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 60 !!!!!! This number of bands might be too low for non-linear optics and real part of linear optics
nstep6 1 nline6 0
kptopt6 1

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 60 60 60 !!!!!! This is much too low : should be at least 24x24x24

acell 3*7.60
ecut 12.00 !!!!!! This is also too low
occopt 3
iscf 3
ixc 3
natom 1 nbdbuf 2
ntypat 1
rprim 0 .5 .5 .5 0 .5 .5 .5 0
xred 3*0.00d0
tnons 144*0.0
typat 1 tolwfr 1.e-20
znucl 13

############################parall##########

# paral_kgb 1
npband 1 npfft 1 npkpt 2
timopt -1
fftalg 401 wfoptalg 4 nloalg 4 fft_opt_lob 2
iprcch 0 intxc 0

Here is the real reflectance spectrum for Al.

Can someone help me to fix this problem? Is there any fault in my input file?

Thanks a lot!

i think you can perform a convergence study of nband to check out if the number you used is too small.

Cheers


Sheleon