Different result getting using CPU & GPU separatley

Dear Sir,

I am working on polymer & water molecules. When I run the same input file using CPU & GPU separately to calculate msd of water in LAMMPS, I get different results in both cases. Why is this happening?

I appreciate any help you can provide.

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Generally speaking, the results from running on CPU and GPU would not be completely same, due to the difference in floating point precision, arithmetic behavior, GPU-specific optimizations, etc. However, the result should be close for a well-behaved setting (a stable system, sufficiently large cell and simulation time, etc.)

More specific comments may be available if you share the complete input file so that others can reproduce it (if it’s not too computationally demanding).

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This is far too vague to provide any specific advice. There are many open questions:

  • How different is “different”?
  • How well converged are those results?
  • What are your specific conditions and system?
  • How are you using the GPU? and what GPU? and using which accelerator package? and how compiled?
  • Which exact LAMMPS version are you using?

Thanks sir

Thank you sir