I did an AIMD run in VASP using 64 cores (32 cores/node) and 250 GB of memory (125 GB/node) for 5 ps (1 fs time step). The calculation took 12.6 hours to complete. CPU efficiency was 99.7% and memory efficiency was 42%.
So I estimated for a 50 ps run with the exact same parameters I would need approximately 126 hours. So I requested 6 days to be safe. Interestingly after 6 days the run timed out and completed only ~22 ps when I checked the output files. CPU efficiency was 98.9% and memory efficiency was 158%!
I don't understand why the memory is getting overloaded and then I guess "slowing" down the calculation once it gets to about 20 ps? Perhaps I'm missing something. Maybe I need more memory and cores? Or can I get around this by simply splitting the 50 ps into individual 10 ps runs?