Dear LAMMPS users and developer team,
I am trying to do NVT and NVE simulation of LiFePO4 using Lammmps (10
Feb 2015 version). I understand I am facing one of the most common
error while working with lammps. I went through many forums discussing
this error and how multiple factors are responsible. I have followed
all the steps mentioned in many forums and re-verified the basic
precautions to be taken while running the lammps script. However, I
still face an issue. I checked each step, irrespective of NVT or NVE
simulation, the temperature increases uniformly in the start and
changes like skyrocket after some temperature (usually around 280K).
While, when I start the simulation with some temperature (given by
velocity command), the temperature decreases in the beginning and
later increases slowly to very high value, resulting again in "lost
atoms" error (in both NVT and NVE case). I also tried increasing the
boundaries slightly, no help.
In my system, I have 5*5*5 supercell of LiFePO4 and Buckingham
potentials with three body harmonic potential parameters using
hybrid/overlay command. I have two sets of structures and force
parameters, taken from literature and I tried all combinations of both
including super-cell derivatives of both structures. I also ran the
simulations with .1fs timestep. Nothing worked. Below is my input
script and please find the attached documents, lfp555.lammps as my one
of initial structure file and lfp.nb3b.harmonic as three body
potentials file and log file after one of the runs.
In this current script, I am doing minimization and NVE in same input
script, whereas I have tried running them independently one after
another, no effect. Please let me know if I am missing anything in the
Lammps input script or making any mistake in syntax. If you suspect
initial structure and parameters are the issue, it will be really
helpful if you could also tell, on what basis you can confirm that or
I can reach that conclusion?
############INITIALIZATION#####################
units metal
dimension 3
boundary p p p
atom_style charge
newton on
################ATOM DEFINITION################
read_data lfp555.lammps
neigh_modify delay 0 every 1 check no
###############SETTINGS#######################
kspace_style ewald 1.0e-4
pair_style hybrid/overlay buck/coul/long 10.0 nb3b/harmonic
pair_coeff 1 4 buck/coul/long 632.1018 0.2906 0.0
pair_coeff 2 4 buck/coul/long 1105.2409 0.3106 0.0
pair_coeff 3 4 buck/coul/long 897.2648 0.3577 0.0
pair_coeff 4 4 buck/coul/long 22764.3 0.149 44.53
pair_coeff 1 1 buck/coul/long 0.000 1.000 0.0
pair_coeff 1 2 buck/coul/long 0.000 1.000 0.0
pair_coeff 1 3 buck/coul/long 0.000 1.000 0.0
pair_coeff 2 2 buck/coul/long 0.000 1.000 0.0
pair_coeff 2 3 buck/coul/long 0.000 1.000 0.0
pair_coeff 3 3 buck/coul/long 0.000 1.000 0.0
pair_coeff * * nb3b/harmonic lfp.nb3b.harmonic 1 2 3 4
minimize 1.0e-4 1.0e-6 100 1000
write_data min.lammps
#thermo_modify lost ignore
fix 1 all nve
thermo 1
thermo_style custom step time temp pe ke etotal fmax
dump 1 all custom 10 nve.lammpstrj id type x y z vx vy vz fx fy fz
timestep 0.0001
run 10000
################END###################################
Thank you,
Saurabh
lfp.nb3b.harmonic (791 Bytes)
lfp555.lammps (106 KB)
log.lammps (373 KB)