begin qpoints ... end in epsilon.inp

[Agathyan Barathi]

In README.md and Input description, instructions have been given to generate the begin qpoints ... end in epsilon.inp, but I couldn't understand how to generate it. Could someone help me to proceed?

4. The dielectric function $\epsilon(q)$ must be calculated for all q-points

   such that $q = k - k'$. For $|q| \ne 0$, all $k$-points are coming from `WFN`.
   In this case, which are the possible $q$-points for $\epsilon(q)$? Use
   `kgrid.x` (and your own editing) to generate the list of $q$-points for
   `epsilon.inp`.  Why do we need to specify $q$-points? What $q$-shift are we

   using?

from input description:

begin qpoints ... end

qx qy qz 1/scale_factor is_q0

scale_factor is for specifying values such as 1/3 is_q0 = 0 for regular, non-zero q-vectors (read val WFNs from WFN) is_q0 = 1 for a small q-vector in semiconductors (read val WFNs from WFNq) is_q0 = 2 for a small q-vector in metals (read val WFNs from WFN) if present the small q-vector should be first in the list You can generate this list with kgrid.x: just set the shifts to zero and use same grid numbers as for WFN. Then replace the zero vector with q0.