#ifdef _OPENACC
subroutine initialisation_openacc

    USE openacc
    
    character(len=6) :: local_rank_env
    integer          :: local_rank_env_status, local_rank

    ! Initialisation of OpenACC
    !$acc init

    ! Recovery of the local rank of the process via the environment variable
    ! set by Slurm, as MPI_Comm_rank cannot be used here
    ! because this routine is used BEFORE the initialisation of MPI
    call get_environment_variable(name="SLURM_LOCALID", value=local_rank_env, status=local_rank_env_status)

    if (local_rank_env_status == 0) then
        read(local_rank_env, *) local_rank
        ! Define the GPU to use via OpenACC
        call acc_set_device_num(local_rank, acc_get_device_type())
    else
        print *, "Error: impossible to determine the local rank of the process"
        stop 1
    end if
end subroutine initialisation_openacc
#endif