CSHIFT = real number (complex shift)default: CSHIFT = 0.1
The implemented Kramers-Kronig transformation uses a small complex shift 
CSHIFT
in Equ. (6.32). The default for
this shift is 0.1, which is perfectly acceptable for most calculations and
causes a slight smoothening of the real part of the dielectric function. If the gap is very small
(i.e. approaching two times CSHIFT), slight inaccuracies in the static dielectric constant
are possible, which can be remedied by decreasing CSHIFT.
If CSHIFT is further decreased, it is strongly recommended to
increase the parameter NEDOS to values around 2000 (see Sec. 6.36).