[lammps-users] ERROR: Lost atoms: original 4200 current 4198

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1

Hi Everyone:
I’m having some problems with the new version of lammps. I got an error and I don’t know what I’m doing wrong. I pasted the input script below . I reduce the time step from 0.015 to 0.00000015 as Paul Cozier suggested me, but It still doesn’t work well. Hope someone can help me.

120600 1.4379556 587.96803 0.010653351 590.1351 0.55263198
120700 1.4397571 587.96788 0.0106795 590.13768 0.55263677
120800 1.4409227 587.96774 0.010705682 590.13931 0.55263979
ERROR: Lost atoms: original 4200 current 4198

########## INPUT SCRIPT ##################
units lj
dimension 3
boundary p p p
neighbor 0.5 bin
neigh_modify delay 5 every 1
atom_style full
bond_style harmonic
read_data in
bond_coeff 1 200.0 1.1
bond_coeff 2 200.0 1.1
bond_coeff 3 200.0 1.1
pair_style lj/cut/coul/long 2.3 25.0
pair_coeff 1 1 1.0 2.0 2.2449240966
pair_coeff 1 2 1.0 1.5 1.6836930724
pair_coeff 1 3 1.0 1.5 1.6836930724
pair_coeff 1 4 1.0 2.0 2.2449240966
pair_coeff 2 2 1.0 1.0 1.1224620483
pair_coeff 2 3 1.0 1.0 1.1224620483
pair_coeff 2 4 1.0 1.5 1.6836930724
pair_coeff 3 3 1.0 1.0 1.1224620483
pair_coeff 3 4 1.0 1.5 1.6836930724
pair_coeff 4 4 1.0 1.5 1.6836930724
kspace_style pppm 1e-4
dielectric 0.17806267
group atom4100 id <> 4100 4100
group atom4200 id <> 4200 4200
group mobile subtract all atom4100 atom4200
fix 1 mobile nve
fix 2 mobile langevin 1.2 1.2 0.01 91290079
thermo_style one
thermo 100
dump system all custom 1000 history tag type xs ys zs ix iy iz
timestep 0.00000015
restart 1000 RESTART
run 1000000

2

Hi Paul.

You may have already tried using the minimizer, but that is one
approach. Another way to run from a cold non-equilibrated start is to
use pair_style soft to push off all of the bad contacts. I also like
starting with a small timestep as you have done, but sometimes that
doesn't work very well.

There's always the possibility that there is something wrong with the
way you've set up your force field. So you might try turning off the
various parts one at a time to see which is causing the crashes.

Also, it looks like your coulombic interactions will be very strong
with dielectric set so small. So really large coulombic forces may be
the culprit. One thing you might try is to gradually ease into the
large coulombic forces by starting the dielectric at, say, 100, and
gradually decreasing the dielectric to where you want it.

If none of this helps, you might try sending us your data file so that
we can try running it here.

Paul Crozier