Pair coefficient

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1

Hello all,
I am a beginner in Lammps. I want to know how to write the data file. Say
for example SPC/E model of water, I found this. Can somebody please
explain the significance of numbers and where do they come from? Thanks
in advance.

Atoms

      1 1 2 -0.8476 1.55000 1.55000 1.50000
      2 1 1 0.4238 1.55000 2.36649 2.07736
      3 1 1 0.4238 1.55000 0.73351 2.07736

Atom type 1 is Hydrogen and 2 is Oxygen. I understand the first 4 columns.
Please help me in understanding the rest ones.

2

This is a snippet of the structure file, not pair_coeff. The last three columns are obviously the cartesian coordinates.

Ray

3

Hello all,
I am a beginner in Lammps. I want to know how to write the data file. Say
for example SPC/E model of water, I found this. Can somebody please
explain the significance of numbers and where do they come from? Thanks
in advance.

have you considered reading the LAMMPS documentation? it is full of
useful pieces of information. especially on rather fundamental subject
like what you are asking about.

the documentation for the read_data command explains the format of the
data file in great detail. there is also a section on simulating
different water models and finally, there is a whole section on pre-
and post-processing tools for LAMMPS on the LAMMPS homepage that
indicates tools that can be used to build initial structures and
convert them to data files.

axel.