[QE-users] GPU version gives different result from CPU version

[Ivan Carnimeo]

Dear Shimin,
unfortunately the test is too large also for me to try it.

Small differences on band gap and total energy can be also due to differences in MPI parallelism used in the CPU and GPU calculations.

If you want to understand more, you can launch the CPU calculation with exactly the same parallelization options as the GPU one (number of MPI ranks, OMP threads, pools, bands, etc...). This will tell you much the error depends on the different CPU/GPU libraries or on the different MPI distribution of the data.

You can also reduce the randomness of the wavefunction initialization with startingwfc='atomic'.

Regards,
IC


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