determinism of CP2K runs

Noam Bernstein noam.be... at nrl.navy.mil
Fri Aug 7 19:49:19 CEST 2009


Hi all - should I expect CP2K Quickstep to be deterministic? I.e. if I  
run twice (in parallel) with exactly the same input file, should the  
results be _exactly_ the same (to all decimals)? Or should I expect  
some random component to the results? Because that's what I'm seeing  
(in a 0 step MD run, i.e. just a single force/energy evaluation),  
despite setting SEED in the GLOBAL section, and I'm trying to figure  
out if that's normal, or indicates a problem in my compiler or machine.
  I've attached a test case that runs in 3 minutes on 16 cores, and  
two outputs (start differing at 39 OT CG, around 1e-10). A much  
smaller system I tried doesn't show the same problem. Is this test  
case still too big? If so, I'll look for a medium size case that shows  
the problem.

											 thanks, Noam

Noam Bernstein
noam.be... at nrl.navy.mil


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