The ABINIT Users Mailing List ( CLOSED )

[giovanni.cantele@na.infn.it]

Dear all,
I was trying to use the optic (4.6.4) program to calculate
linear dielectric functions for some systems.

As a check, I'm studying bulk Si, but I cannot obtain
results consistent with the literature.
I've tried to get convergence with respect to the cutoff and/or
k-point mesh, with no success. For example, the transition at Gamma
point is never present in the epsilon2.

Nevertheless, looking at the sources, it seems that
a problem in the module (or in the way I use it!) is present.
In fact, the log file of the optic run always prints, in my case,
 fermie            =   0.00000 Ha   0.00000 eV
Then, I tried to set the Fermi energy by hand in the optic.F90,
obtaining results which are similar to those found in the literature.

So, the question is: is there a problem in the reading of the Fermi
energy in the optic program or this problem could be due to wrong settings
in some of the input files?

One more question: the output of optic contains lines like

 # Energy(eV)         Im(chi1(w))
 #calculated the component:  1  1of linear susceptibility

Just to be sure: does the output actually contain the dielectric function
espilon?
Within linopt I found

eps(iw)=1.d0+4.d0*pi*chi(iw)
...
write(92, '(2es16.6)' ) ene,aimag(eps(iw))


Thanks for help
Giovanni