problem scaling multiple walker metadynamics using many nodes

[lar... at lbl.gov]

Dear all,

I am running a multiple walker metadynamics simulation using FARMING. 
Specifically, I use 6 replicas and submit the FARMING job to 6 nodes with 
68 cores each (see the file *inp* attached here). The simulation runs fine, 
but I don't seem to be able to speedup the calculation using more than one 
node per walker (i.e. per individual job). I tried submitting the job to 
twice as many nodes, hoping that cp2k would assign 2 nodes per replica, but 
that doesn't speed the simulation at all. I have also tried using  
"GROUP_PARTITION 136 136 136 136 136 136" but that doesn't work either. I 
know there is an issue because when I run a simple simulation (i.e. no 
farming) of the same system I see a very clear speedup when going from 1 to 
2 nodes.

Any ideas on how to make this work?

Thanks!
Luis
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