[lammps-users] Unknown identifier in data file

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1

Hi, LAMMPS users,

I generate a data file as an input. ALMMPS gave me this error message:

ERROR on proc 0: Unknown identifier in data file: 1582 1 555 567

I searched the mailing list, I found Steve had answer one related question on Feb 19 as:

That line appeared when LAMMPS was expecting a text string
like Bonds or Atoms. So something is messed up in your data file.

In my case, the line LAMMPS complained is for bond information, and it is the middle, I can’t understand why LAMMPS complained it.

Part of mt data file is:

3456 atoms
4752 bonds

2 atom types
1 bond types

0 70 xlo xhi
0 70 ylo yhi
0 70 zlo zhi

Masses

1 12
2 12

Atoms

1 1 -24 -24 -24 -1 1
2 1 -24 -20 -24 -1 1
3 1 -24 -16 -24 -1 1
4 1 -24 -12 -24 -1 1
…

Bonds

1 1 1 2
2 1 1 13
3 1 1 145
4 1 2 3
5 1 2 14
…
1576 1 553 565
1577 1 553 697
1578 1 554 555
1579 1 554 566
1580 1 554 698
1581 1 555 556
1582 1 555 567
1583 1 555 699
1584 1 556 557
1585 1 556 568
…
4749 1 1724 1725
4750 1 1725 1726
4751 1 1726 1727
4752 1 1727 1728

Can anyone tell me what’s wrong in my data file? Thanks!

All the best!

Dongsheng

2

Dongsheng,

It is clear that something is wrong with your data file. It is not
clear what the problem is. The usual suspects are:

1) Mismatch between declared number of atoms/bonds/etc and the number
listed in the data file.
2) Wrong number of empty lines before/after each section in the data file.
3) Erroneous characters accidentally left floating around.
4) Wrong number of entries on a given line or lines.

If you're still unable to figure out what is wrong with your data
file, you might try posting it to the users list, or if it is larger
than 200 kb, you could send it to just me.

Paul

3

Your data file has these lines in the Atoms section:

143 1 20 16 -24 -1 1
144 1 20 20 -24 -1 1
1729 2 -18.0195 -34.0571 -8.18028 1 2
1730 2 -5.97431 -30.2562 34.5189 1 3

So there is big missing chunk of atoms, not the 3456 atoms
the header of the file indicates is there.

Steve