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I run VASP on a Athlon Linux cluster compiled with the makefile:

makefile.linux_ifc_ath

and on the Jülich IBM cluster JUMP running on POWER6

For a calculation on LiCoO2 on those two machines I get two different TOTEN for the same input namely:

-335.795219 eV on JUMP
-335.916387 eV on the Athlon cluster

I have no idea, what the problem might be. I tried different optimizations (O3 and O2) without any effect on the JUMP Cluster. But I had to use O2 on the athlon cluster to get the same energy result for parallel and serial calculations.

Thanks in advance

1) please check if the number of bands were the same for both runs.

2) To test whether the error is due to optimization, re-run with lowest optimization level on both machines.

3) Otherwise, there may e.g. be an error in one of the libraries (LAPACK, BLAS) on one of the machines.

I have the same problem on IBM Power6, i.e., the calculated total energy is wrong when I use -O3 or -O2. As expected, if the optimiztion level is changed to the lowest one (-O0), the energy is correct. I think some subroutines need the lowest optimiztion level, but it is diffucult to identify them. Does anybody have a clue?

Thanks.