> For the complete documentation index, see [llms.txt](https://particle-analytics-1.gitbook.io/iota-user-manual/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://particle-analytics-1.gitbook.io/iota-user-manual/simulation_data_interfaces/support_liggghts/using_liggghts_dump.md).

# LIGGGHTS-DUMP

The dump files generated by [LIGGGHTS](http://www.cfdem.com/liggghts-open-source-discrete-element-method-particle-simulation-code), for the particles, can have any selection of variables. However, to be processed in Iota a minimum number of variables is required and the order is fixed. The same restriction affect the [LIGGGHTS](http://www.cfdem.com/liggghts-open-source-discrete-element-method-particle-simulation-code) particle-particle and particle-geometry contacts files

In the particles file, the filename must have the extension ".p". The variables in the command must follow :

* *id*: column one
* *type*: column two
* *x,y,z*: columns three to five
* *vx,vy,vz*: columns nine to eleven
* *radius*: column eighteen

The rest of columns will be considered as user defined variables, and will be processed in that way. An example of the [LIGGGHTS](http://www.cfdem.com/liggghts-open-source-discrete-element-method-particle-simulation-code) dump command for the particles file is:

```
dump Pfile all custom 400 dumpfile.p id type x y z ix iy iz vx vy vz fx fy fz &
  omegax omegay omegaz radius
```

The particle-particle contacts file must have the extension ".c". In this file, just the IDs of particles in contact and forces will be read:

* id: IDs of particles in contact. Columns seven to nine
* fx,fy,fz: Contact forces. Columns two ten to twelve

The rest of the columns will not be considered.

In the case of the particle-geometry contact files must have the extension ".w". The rules for such files are similar to the particle-particle contact files, with a condition on the contact point position:

* *cx,cy,cz*: Contact point position. Columns one to three
* *id*: IDs of particles in contact. Columns seven to nine
* *fx,fy,fz*: Contact forces. Columns ten to twelve

An example of the [LIGGGHTS](http://www.cfdem.com/liggghts-open-source-discrete-element-method-particle-simulation-code) dump command for both contact files is:

```
compute cp all pair/gran/local id pos force
compute cw all wall/gran/local id pos force
dump Cfile all local 400 dumpfile.c c_cp[1] c_cp[2] c_cp[3] c_cp[4] c_cp[5] &
  c_cp[6] c_cp[7] c_cp[8] c_cp[9] c_cp[10] c_cp[11] c_cp[12]
dump Wfile all local 400 dumpfile.w c_cw[1] c_cw[2] c_cw[3] c_cw[4] c_cw[5] &
  c_cw[6] c_cw[7] c_cw[8] c_cw[9] c_cw[10] c_cw[11] c_cw[12]
```

In the case of the CAD wall/geometries, the only restriction is that all the meshes to be processed should be contained in a single stl file per time-step for the case of moving CAD walls/geometries. In the case of static CAD wall/geometries, it is possible to just provide a single stl file for the processing.

Example of the [LIGGGHTS](http://www.cfdem.com/liggghts-open-source-discrete-element-method-particle-simulation-code) dump command for moving and static CAD wall/geometries files are:

* Static meshes:  `dump dmpstl all mesh/stl 400 dump.stl`
* Moving meshes:  `dump dmpstl all mesh/stl 400 dump*.stl`