Include bpm/sphere to OVITO's readable LAMMPS atom styles

OVITO Feature requests
,
1

I’m using OVITO Basic version 3.10.3. I’m trying to read a LAMMPS data file generated with atom_style bpm/sphere. It turns out that bpm/sphere is not a recognized style in OVITO, though it is a readable style using read_data in LAMMPS. In a pinch, I can delete the second column in the data file (specifying molecule-ID) and it can then be read as a sphere atom style, and it is still able to display bonds despite there being no bonding in atom_style sphere. It would be convenient if OVITO could handle this type of data file to support its claim that it can “load files conforming to the format specification of the LAMMPS read_data command.” (LAMMPS data file reader — OVITO User Manual 3.13.0 documentation)

2

Yes, I/O support for bpm/sphere atom style is missing in OVITO. I don’t know for sure, but my guess is that this atom style didn’t exist in LAMMPS when we last reworked OVITO’s data file reader and implemented support for the current styles. But that’s something we can probably add very quickly to the next program release.
Would you be willing to make your data file available to us for testing purposes? In case you cannot upload it here, please send it to [email protected]. Thank you!

3

Sure. I’m a new user here and appear to be unable to upload files, but I’ll put the contents of a minimal version in here:

1 atom types
1 bonds
1 bond types

-1.5 2 xlo xhi
-1.5 2 ylo yhi
-1.5 2 zlo zhi

Atoms # bpm/sphere

1 0 1 1 1 0 0 0 0 0 0
2 0 1 1 1 0.4183108659889671 -0.4369953299751148 0.7962732577297201 0 0 0

Velocities

1 0 0 0 0 0 0
2 0 0 0 0 0 0

Bonds

1 1 1 2

Thank you for your quick response! I look forward to this feature being available.

4

In your sample file, the first two lines are missing, right? A comment line and the number of atoms:

# LAMMPS data file
2 atoms

And I am wondering why this section has 7 columns:

Velocities

1 0 0 0 0 0 0
2 0 0 0 0 0 0

The LAMMPS documentation says the Velocities section should have this format:

atom-ID vx vy vz

Perhaps you can clarify this, thank you.

5

The three extra columns in the Velocities section must be the angular velocities of the spherical particles, right? It looks like the LAMMPS docs forgot to mention that the bpm/sphere style uses this format, similar to the sphere style.

6

This is a development build of OVITO Basic 3.13.1 for you to test, which includes support for the missing bpm/sphere atom style. Please let me know if you encounter any issues.

ovito-basic-3.13.1-dev-8521e73c-win64-dev3.13.1.exe
ovito-basic-3.13.1-dev-8521e73c-x86_64-dev3.13.1.tar.xz
ovito-basic-3.13.1-dev-8521e73c-macos-arm64-dev3.13.1.dmg

9

Thank you very much for sharing the development build! I tested it, and it works great!

You’re right about the missing header and atoms line. My bad. I copied it from my terminal and missed the top few lines:

LAMMPS data file via write_data, version 12 Jun 2025, timestep = 0, units = lj

2 atoms

I’m not sure what the extra 3 columns are in Velocities and Atoms sections, but it also seems to be generated in the sphere style, and doesn’t appear to affect reading in LAMMPS or OVITO either way.

10

Ok, great. Thanks for confirming that it works.