Dear Anuja
the calculation with a very dense k-point mesh is most likely looping
through the k points and taking a lot of time before printing out anything.
It is not necessary though to run the scf calculation with the very fine
mesh; it is sufficient to run the scf calculation with a feaisble k
point mesh for which you are confident to be at convergens, once done
the scf calculation with the feasible converged mesh you may run nscf
calculation with the finer mesh that you need for the epsilon.x
calculation.
To speed up the calculation you may try to use the k-point parallelism:
in suppose that you are using 20 MPI processes and that 4 of them are
sufficient to run the iterative diagonalization for one k point, you can
divide your 20 MPI processes in 5 pools each diagonalizing and assigned
subset of the total k points. To do this you just have to run your pw.x
command as:
mpirun -np 20 pw.x -nk 5 -i input_nscf > out_nscf
I hope this helps.
kind regards - Pietro
On 01/07/19 17:44, Anuja Chanana wrote::
Dear all,
I am trying to run epsilon.x by reading the following tutorial
https://www.paradim.org/sites/default/files/2019-05/Band_Structure_and_UV-VIS_Spectra.pdf
The manual says that for the calculation of epsilon, a finer-k mesh is
required like 30x30x30.
I have a triclinic system where
a = 6.3 A b = 6.5 A c = 5.9 A
alpha 121.358 beta 88.3349 gamma 106.391
If I increase the k-mesh to 30x30x30, the initial scf simulation
doesn't run at all.
Nothing gets written. Why does that happen?
Has anyone experienced it before?
Thanks
Anuja
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