Non-numeric box dimensions - simulation unstable

LAMMPS LAMMPS Beginners
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1

Hello!
I am trying to simulate 4 chains of polymers with salt and MOF using LAMMPS. I get an error while doing simulation in NPT. Although with the same input I have simulated polymers and salt but when I added MOF it is giving an error I don’t understand that why I am getting an error. Can any one explain me?

ERROR on proc 0: Non-numeric box dimensions - simulation unstable (…/pppm.cpp:1885)
application called MPI_Abort(MPI_COMM_WORLD, 1) - process 0

LAMMPS (29 Oct 2020)

Here is my input file

Defining the system

units metal
boundary p p p
atom_style full
#dielectric 1
bond_style harmonic
angle_style harmonic
dihedral_style opls
improper_style cvff
#special_bonds lj 0.000000 0.000000 1.000000 coul 1.000000 1.000000 1.000000
pair_style lj/cut/coul/long 12.0
pair_modify table 16 # Accuracy of the table used for real space electrostatics
pair_modify mix arithmetic
pair_modify tail no
box tilt large
read_data “/home/lammps/lammps_min_polymer_mof.dat”
kspace_style pppm 1e-6
neighbor 2.0 bin
neigh_modify delay 0 every 1 check yes

Setting for output

dump Dump all custom 1000 “min.lammpstrj” id type x y z ix iy iz vx vy vz
thermo_style custom step time cpu pe ke etotal enthalpy temp press vol density cella cellb cellc cellalpha cellbeta cellgamma
thermo 100

Setting to run MD or minimization

>>> SCHEME-1

restart 1000 restart.min
minimize 1.0e-10 1.0e-8 10000 100000
run 10000

Here is my NPT file

Defining the system

units metal
boundary p p p
atom_style full
#dielectric 1
bond_style harmonic
angle_style harmonic
dihedral_style opls
improper_style cvff
#special_bonds lj 0.000000 0.000000 1.000000 coul 1.000000 1.000000 1.000000
pair_style lj/cut/coul/long 12.0
pair_modify table 16 # Accuracy of the table used for real space electrostatics
pair_modify mix arithmetic
pair_modify tail no
#box tilt large
read_restart restart.min.15000
#read_data “/home/lammps/lammps_min_polymer_mof.dat”
kspace_style pppm 1e-6
neighbor 2.0 bin
neigh_modify delay 0 every 1 check yes
write_restart restart.npt
velocity all create 5.0 30247
dump Dump all custom 1000 “traj_npt_5K.lammpstrj” id type x y z ix iy iz vx vy vz
thermo_style custom step time cpu pe ke etotal enthalpy temp press vol density cella cellb cellc cellalpha cellbeta cellgamma
thermo 100
fix ensemble1 all npt temp 5.0 5.0 0.1 aniso 1.0 1.0 1.0
timestep 0.002
restart 50000 restart.npt
run 100000
unfix ensemble1

Thanks in advance

2

According to the LAMMPS Error messages page, this error is because “the box size has apparently blown up” (see 11.5. Error messages — LAMMPS documentation).

Maybe your initial microstate is a bit messed up? How did you add the MOF? Was there some overlapping between atoms?
It could also be that maybe your potential parameters (particularly for the MOF) are incorrect?

Also, in a quick search, I saw someone reporting problems with the Nose-Hoover barostat at low tempeartures (Simulation halts at low temperature in NPT), but I dont know enough to judge this unfortunately. It might be worth checkign out.

1 Like
3

Hi Faiza,

Maybe you already solved your problem, but what often helps me to figure out what is going on when I get error messages is to run a shorter simulation in which I output the data every timestep. Often if the simulation is unstable, the problem will already present itself in the first steps.

I then visualize the output so that I can eyeball whether anything very obvious is wrong. Did you already try this? In your input I see that you output your thermo every 100 steps and the trajectory every 1000 steps.

Hope it helps!

Kind regards,
Justina

2 Likes
4

Thank you for your suggestion. I will try this and let you know.

Kind regards,
Faiza