NaN error and integer overflow in number of atoms

[minitu]

Hello,
I'd like to report two errors that I observed when running the MPI + Kokkos version of MiniMD (miniMD/kokkos).

The first error is the T and P values showing up as NaN, which causes some kernels to run abnormally fast.
The configuration is as the following, executed on 32 nodes of OLCF Summit:

$ jsrun -n192 -a1 -c1 -g1 -K3 -r6 -M -gpu ./miniMD -i in.lj.miniMD -gn 0 -nx 768 -ny 768 -nz 384 -n 100
# Create System:
# Done ....
# miniMD-Reference 1.2 (MPI+OpenMP) output ...
# Run Settings:
        # MPI processes: 192
        # Host Threads: 1
        # Inputfile: ../inputs/in.lj.miniMD
        # Datafile: None
# Physics Settings:
        # ForceStyle: LJ
        # Force Parameters: 1.00 1.00
        # Units: LJ
        # Atoms: 905969664
        # Atom types: 8
        # System size: 1289.93 1289.93 644.96 (unit cells: 768 768 384)
        # Density: 0.844200
        # Force cutoff: 2.500000
        # Timestep size: 0.005000
# Technical Settings:
        # Neigh cutoff: 2.800000
        # Half neighborlists: 1
        # Team neighborlist construction: 0
        # Neighbor bins: 460 460 230
        # Neighbor frequency: 1000
        # Sorting frequency: 1000
        # Thermo frequency: 100
        # Ghost Newton: 0 
        # Use intrinsics: 0
        # Do safe exchange: 0
        # Size of float: 8

# Starting dynamics ...   
# Timestep T U P Time
0 nan -6.773368e+00 nan  0.000
100 nan 0.000000e+00 nan  1.138


# Performance Summary:
# MPI_proc OMP_threads nsteps natoms t_total t_force t_neigh t_comm t_other performance perf/thread grep_string t_extra
192 1 100 905969664 1.137955 0.050640 0.000000 0.671161 0.416153 79613833194.819092 414655381.223016 PERF_SUMMARY 0.000000

The second error is an integer overflow error in the total number of atoms, with large problem sizes:

$ jsrun -n1536 -a1 -c1 -g1 -K3 -r6 -M -gpu ./miniMD -i in.lj.miniMD -gn 0 -nx 1536 -ny 1536 -nz 768 -n 100
# Create System:
# Done ....
# miniMD-Reference 1.2 (MPI+OpenMP) output ...
# Run Settings:
        # MPI processes: 1536
        # Host Threads: 1
        # Inputfile: ../inputs/in.lj.miniMD
        # Datafile: None
# Physics Settings:
        # ForceStyle: LJ
        # Force Parameters: 1.00 1.00
        # Units: LJ
        # Atoms: -1342177280
        # Atom types: 8
        # System size: 2579.86 2579.86 1289.93 (unit cells: 1536 1536 768)
        # Density: 0.844200
        # Force cutoff: 2.500000
        # Timestep size: 0.005000
# Technical Settings:
        # Neigh cutoff: 2.800000
        # Half neighborlists: 1
        # Team neighborlist construction: 0
        # Neighbor bins: 921 921 460
        # Neighbor frequency: 1000
        # Sorting frequency: 1000
        # Thermo frequency: 100
        # Ghost Newton: 0
        # Use intrinsics: 0
        # Do safe exchange: 0
        # Size of float: 8

# Starting dynamics ...
# Timestep T U P Time
0 1.440000e+00 3.657619e+01 -6.220309e+00  0.000
100 1.435069e+00 3.657569e+01 -6.219723e+00  2.041


# Performance Summary:
# MPI_proc OMP_threads nsteps natoms t_total t_force t_neigh t_comm t_other performance perf/thread grep_string t_extra
1536 1 100 -1342177280 2.040788 0.056916 0.000000 0.852597 1.131275 -65767589680.726250 -42817441.198389 PERF_SUMMARY 0.000000