NEB images not generating properly

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1

Hi all,

I am trying to run an NEB simulation for simple 3 Argon atoms on lammps-16th March 2018 version. When I run the calculation, at the first step before the calculation starts, my RDT=0, RD1=0 and all RDN (N = 2 to N) = -nan. The Potential energy of all my images comes out to be the same (as initial) at all the steps.
This means that all the images have the same initial configuration (which I do not want). There is probably some small thing that I am doing wrong somewhere, but I can't seem to figure out what. I ran the example script given. It runs perfectly and I can't seem to figure out any difference in the two which would cause such a mistake to happen. I am attaching my script here for your reference.

units real
boundary p p p
atom_style molecular
read_data configurations.data

pair_style lj/cut 10.215
pair_coeff * * 1 1

minimize 1.0e-6 1.0e-4 1000 10000
reset_timestep 0
timestep 0.05

neigh_modify every 10 delay 20 check yes
thermo 300
fix 1 all neb 1.0 parallel ideal
min_style quickmin
neb 0.0 0.1 1000 1000 100 final last.txt
dump 1 all atom 1000 dump

Thanks a lot for your time and help in advance,
Madhur Aggarwal

2

Madhur,

RDT cannot equal zero. This is the total reaction coordinate. Your replica reaction coordinates, RD1, RD2, ..., RDN, are normalized by dividing by this quantity. Division by zero returns NaN. Double check that your "last.txt" replica does not contain identical coordinates to your data file "configurations.data".

-Keith

3

Hi Keith,

My apologies for replying this late. I was out due to some emergency and didn't have access to the internet.

I checked my configurations.data and last.txt files, they do not have the same coordinates. I am attaching the files here as well for your reference.

-Madhur

configurations.data (499 Bytes)

last.txt (90 Bytes)

4

Hi Keith,

I figured out what the issue was. There was an error in my last.txt file. I had written "N=3" in the first line where we specify the no of lines to follow, instead of just 3.

Thanks a lot for your time and help,
Madhur