# Running QuantumATK Under Cray MPI (aprun)¶

ATK is compiled against MPICH3 on Linux, but can be run on any platform compatible with that library structure, like Intel MPI and MVAPICH. It is also possible to run ATK under Cray MPI, but it requires some special configuration. Some of this is very system-specific, so the comments below may or may not be relevant in all cases, but they should provide enough hints for figuring out how to run QuantumATK properly under “aprun”.

The following points have been relevant on other Cray systems (the details regarding version numbers etc are of course system-specific).

1. It is crucial to use an ABI-compatible MPI module. This can be achieved with something like the following lines:

module unload PrgEnv-pgi PrgEnv-gnu PrgEnv-cray PrgEnv-intel
module swap cray-mpich cray-mpich-abi/7.3.0

On another system the following lines were used:

module unload PrgEnv-cray

export LD_LIBRARY_PATH="${CRAY_LD_LIBRARY_PATH}:${LD_LIBRARY_PATH}"