Lammps ouput "nan"

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1

Dear professors,

I am trying to simulate water, and it outputs "nan". I am sure that their is no atom overlap in the initial configuration. I have tried different ways and also tried to find answer in the mail list, but I failed.

The followings are the codes and errors. The simulation is very simple, and I want to see the increase of water temperature.

Best wishes,

Xiaohui

******************************Codes**********************
units real
dimension 3
boundary p p p

atom_style full
neighbor 0.5 bin
neigh_modify every 1 delay 2 check yes

####create geometry

read_data water_box.data

#potentials

pair_style lj/charmm/coul/charmm 9 10
bond_style harmonic
angle_style harmonic

pair_coeff 1 1 0.1521 3.1507 #O-O epsilon sigma
pair_coeff 2 2 0.046 0.4 #H-H epsilon sigma
pair_coeff 1 2 00836 1.7753 #O-H epsilon sigma
bond_coeff 1 450 0.9572 #O-H
angle_coeff 1 55 104.52 #H-O-H

#min_style sd
minimize 1.0e-8 1.0e-8 1000 10000

#fix 0 all shake 0.0001 20 0 b 1 a 1

fix 1 all npt temp 300 300 100 aniso 1 1 1000 drag 1.0

thermo_style custom step temp press ke pe etotal

timestep 1 #unit fs
thermo 1000
run 10000

unfix 1

fix 1 all npt temp 300 373 100 aniso 1 1 1000 drag 1.2

dump 1 all atom 1000 water.lammpstrj

run 20000

**************************output results**************************************
Step Temp E_pair E_mol TotEng Press Volume
1000 0 -4781436.8 299424.98 -4482011.9 5586.6588 125000
2000 -nan 0 -nan -nan -nan -nan
3000 -nan 0 -nan -nan -nan -nan
4000 -nan 0 -nan -nan -nan -nan
5000 -nan 0 -nan -nan -nan -nan
6000 -nan 0 -nan -nan -nan -nan
7000 -nan 0 -nan -nan -nan -nan
8000 -nan 0 -nan -nan -nan -nan
9000 -nan 0 -nan -nan -nan -nan
10000 -nan 0 -nan -nan -nan -nan
11000 -nan 0 -nan -nan -nan -nan

2

Dear professors,

I am trying to simulate water, and it outputs "nan". I am sure that their is no atom overlap in the initial configuration. I have tried different ways and also tried to find answer in the mail list, but I failed.

The followings are the codes and errors. The simulation is very simple, and I want to see the increase of water temperature.

there are two main possible explanations:
1) there is still something *very* wrong in your initial structure
2) there is something wrong with your executable.

the second you can easily check by running a known to work input using
similar features, e.g. this one
http://git.lammps.org/git/?p=lammps-icms.git;a=tree;f=bench-accel/bench_spce;hb=HEAD
or the rhodo benchmark from the LAMMPS distribution

if point 2) works, you have to look more carefully at your input
topology. it is impossible to do this from here.

axel.