Unknown error during Geometry Optimization

Hello,
I am trying to run a Geometry Optimization on a system with 60 polymer chains of 1000 beads each and spherical nanoparticles. I am getting the following error message : "APPLICATION TERMINATED WITH THE EXIT STRING: Killed (signal 9)" .
I was able to run geometry optimization in other similar systems, it happens only for this specific system with larger nanoparticles.
Does anyone have an idea of what this might be ?

Thank you,

Lola