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# LAMMPS dump local file reader

For loading per-bond data from files written by the dump command of the LAMMPS simulation code.

## Supported format variants

The reader specifically handles files written by the LAMMPS dump style local. Since such files only store per-bond information but no particle data, the file reader is typically used in conjunction with a Load trajectory modifier to amend an already loaded particle model with varying bonds, e.g. from a reactive MD simulation.

The reader can parse gzipped files (“.gz” suffix) directly. Binary files (“.bin” suffix) are not supported.

## Column-to-property mapping

The different data columns in a dump local file must be mapped to corresponding bond properties within OVITO during file import. Since OVITO cannot guess the right mapping automatically in almost all cases (because file columns have user-defined names), you usually have to specify the correct mapping by hand in the following dialog displayed by the file reader:

For further information on how to set up the bond property mapping correctly, see the Load trajectory modifier.

## Python parameters

The file reader accepts the following keyword parameters in a call to the load() Python function:

columns (list[str|None]) – A list of OVITO bond property names, one for each data column in the dump local file. List entries may be set to None to skip individual file columns during parsing.