BZ energy RIM analyzer (ypp r)
Default options 
bzrim   #   BZ energy RIM analyzer 
BZ_RIM_path= "."   #   Path to the SAVE folder with the RIM DB1 
BZ_RIM_Nk=0   #   BZ Random Integration points 
cooOut= "rlu"     Points coordinates (output) cc/rlu/iku/alat 

Kpoints units 
cc  Cartesian coordinates  
rlu  reduced lattice coordinates or crystal coordinates  
alat  Cartesian coordinates in units of the lattice parameter "a"  
iku  integer reduced lattice units (internal Yambo units)  
Example: How to speedup dielectric constant convergence using ERIM
Here we show how to use ERIM approach to speedup the calculation of dielectric constants,
for more details see Andrea Marini
thesis at page 67.
 Start with a small grid, for example 2x2x2, not enough to get a converged epsilon in bulk Silicon
 Use ypp r to generate random kpoints in the Brillouin zone, for example generate 2000 points by setting BZ_RIM_Nk=2000
 Give the list of kpoints to ABINIT (or PWSCF) and calculate the wavefunctions on these points.
Notice that the bands that make difficult the convergence of dielectric constant are the ones close to the gap
so for example if in your regular sampling (2x2x2 in our case) you used 30 bands, for the random kpoints it is
sufficient to calculate only the first 10 bands for each kpoint (Silicon has 4 valence, so 6 conductions are enough).
 Read the energies without the wavefunctions a2y w (or p2y w )
 Create the ERIM database: go in the folder of point 1) make ypp r, and set the path to the SAVE folder relatively to the
calculation of the electronic bands over the random kpoints BZ_RIM_path= "/scratch/Silicon/randomk."
 ypp will read the random kpoints and divide them according to their distance from the points on the regular grid (2x2x2),
it will print also the minum and maximum number of random kpoint for each point of the grid
....
<> :: BZ blocks filling : 10 23
...
and create the database SAVE/ndb.E_RIM.
 calculate again the dielectric constant, using the ERIM to average the denominators, this time the dielectric constant will converges very very fast, and you will find in the file o.eps_q1_inv_rpa_dyson a line like
....
# BZ Energy RIM points : 2008
....
that indicates the average on the random kpoints.
Probably the 2x2x2 grid is not enought even with ERIM, but this example gives you and idea of ERIM works. Moreover
other properties that depend from the integral of ε(q,ω), as G_{0}W_{0} corrections, will converge even faster.
The same approach works also for the
BetheSalpeter equation using the
inversion solver y i, see also
" Speeding up the solution of the BetheSalpeter equation by a doublegrid method and Wannier interpolation ".
Notice that the calculation becomes slower, because for each kpoint
the Green's functions are averaged on the random kpoints, see also
http://www.yambocode.org/doc/../theory/docs/doc_Xd.php and the PhD thesis of A. Marini.