Yambo Community Forum

Dear all,

I am trying to run Yambo on a large system (832 electrons) with low accuracy to examine the scaling and convergence. However, my runs often crash with the following message in some of the log files:

<02s> P75: [05] Coloumb potential CutOffslab
P75: [ERROR] STOP signal received while in[05] Coloumb potential CutOffslab
P75: [ERROR] Reading File ./gw_rimw_ppa_3Ry_gap//ndb.cutoff; Variable NOT DEFINED; NetCDF: Unknown file format

I tried examining what causes the crash, but I can't figure it out as it sometimes works and sometimes not (e.g. the same code with NGsBlkXp=2Ry instead of 3Ry worked fine). Please find the relevant files attached.

Kind regards,
Stefan Velja
PhD Student
Carl von Ossietzky University of Oldenburg

Dear Stefan

this crash can be due to a memory problem, I propose you some possible solutions:

1) compile Yambo with the openMP support using --enable-open-mp and then run calculations
using 2 or 4 threads, typically setting OMP_NUM_THREADS=2 or 4, this will double or quadruple the available memory

2) parallelize your calculation on bands, add the flag "-V par" in the input generation and set all parallelization
on valence and conduction bands

3) increase the number of G-vectors much slowly, for example use:
NGsBlkXp=2000 mRy, then NGsBlkXp=2200 Ry and so on

4) decrease the total numer of G-vectors in the calculation, add the flag "-V RL" in the input generation
and decreasi FFTGvecs to 1/2 or 1/3 of its value. You can check the effect recalculating optics "yambo -o c -V RL" with different number of G-vectors,
and see it the dipoles (and the spectrum) change.

best
Claudio

Dear Stefan,
I'm not sure you this is a memory problem,
it seems you have just 1 k point and I suspect that the rimW can have problem in this situation (e.g. problem in interpolating W).

What's the reason behind using rimW and slab-z geometry with a gamma only calculation?

Best,
Daniele