unknown identifier in data file

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1

Hello,

I’m running lammps for a polymer system. I keep getting the error message of:

UNKNOWN: 16 2 1 0.0 -0.1673 -1.1293 1.0915 0 0 0
ERROR: Unknown identifier in data file

I cannot find what’s wrong in my data file. Here is a test data file for which I get the above error :

LAMMPS Description

20 atoms
18 bonds
0 angles
0 dihedrals
0 impropers

1 atom types
1 bond types

-1.584757 1.584757 xlo xhi
-1.584757 1.584757 ylo yhi
-1.584757 1.584757 zlo zhi

Masses

1 1.0

Atoms

1 1 1 0.0 -0.9642 0.6272 -0.5195 0 0 0
2 1 1 0.0 -0.7273 0.8255 0.4000 0 0 0
3 1 1 0.0 0.0773 0.4218 0.7614 0 0 0
4 1 1 0.0 0.4053 1.1782 1.2724 0 0 0
5 1 1 0.0 -0.2345 -1.5553 0.6880 0 1 0
6 1 1 0.0 -1.0726 1.1282 0.6408 0 0 0
7 1 1 0.0 1.3049 1.1616 0.0818 -1 0 0
8 1 1 0.0 0.6310 0.4944 -0.1223 -1 0 0
9 1 1 0.0 -0.1325 0.8312 0.3721 -1 0 0
10 1 1 0.0 0.5098 1.5573 0.3391 -1 0 0
11 2 1 0.0 0.1742 -1.3342 -0.2460 0 0 0
12 2 1 0.0 -0.5267 1.4924 0.3303 0 -1 0
13 2 1 0.0 -0.4575 0.8156 1.0218 0 -1 0
14 2 1 0.0 -0.6371 -1.4515 1.3289 0 0 0
15 2 1 0.0 0.1473 1.5720 -1.2888 0 -1 1
16 2 1 0.0 -0.1673 -1.1293 1.0915 0 0 0
17 2 1 0.0 0.3641 1.5408 -1.4383 0 -1 1
18 2 1 0.0 0.9139 0.7434 -1.4896 0 -1 1
19 2 1 0.0 -1.5541 0.7141 -0.8203 1 -1 1
20 2 1 0.0 -0.9888 0.1807 -0.2400 1 -1 1

Bonds

1 1 1 2
2 1 2 3
3 1 3 4
4 1 4 5
5 1 5 6
6 1 6 7
7 1 7 8
8 1 8 9
9 1 9 10
10 1 11 12
11 1 12 13
12 1 13 14
13 1 14 15
14 1 15 16
15 1 16 17
16 1 17 18
17 1 18 19
18 1 19 20

2

Hello,

I'm running lammps for a polymer system. I keep getting the error message
of:

UNKNOWN: 16 2 1 0.0 -0.1673 -1.1293 1.0915 0 0 0
ERROR: Unknown identifier in data file

I cannot find what's wrong in my data file. Here is a test data file for
which I get the above error :

it is likely not the data file, that is at fault,
but you are using the wrong atom style.
which one do you use?

if your atom style requires less data fields,
then read_data comes up short will produce
the exact type of error that you describe.

axel.

3

I modified the input file of lammps’ example for setting up the initial configuration which initially had the format of
Polymer chain definition

0.6281331503 rhostar
53689748 random # seed (8 digits or less)
1 # of sets of chains (list blank line + 6 values for each set)
0 label chains with molecule #

16 number of chains
50 monomers/chain
1 type of monomers (for output into LAMMPS file)
1 type of bonds (for output into LAMMPS file)
0.97 distance between monomers (in reduced units of sigma)
1.02 no distance less than this from site i-1 to i+1 (reduced unit)

to:

Polymer chain definition

0.6281331503 rhostar
53689748 random # seed (8 digits or less)
1 # of sets of chains (list blank line + 6 values for each set)
0 label chains with molecule #

2 number of chains
10 monomers/chain
1 type of monomers (for output into LAMMPS file)
1 type of bonds (for output into LAMMPS file)
0.97 distance between monomers (in reduced units of sigma)
1.02 no distance less than this from site i-1 to i+1 (reduced unit)

and then did the run with tools/setup_chain (used the original lammps program)

why does it produce different formats for the out put in the original one, each line under Atoms has 7 data points, and in what I got each line under Atoms has 10 data points.

4

If you are talking about the tools/chain.f program then
it writes out 9 fields per Atoms line. Look at line 260
of chain.f. So I don't know how you got the output you
list in your data file. The 9-field version is compatible
with atom_style bond in a LAMMPS input script.

Steve