# Writing molecular dynamics data to binary LAMMPS format

In this post I will explain  how to write to the binary LAMMPS file format from C++, using data stored in Armadillo vectors and matrices. After running the example in this post you should be able to open the resulting file in Ovito or any other program capable of reading binary LAMMPS files. The example should also be fairly easy to port to other data structure type, if needed.

For the impatient: You’ll find a working main.cpp file and a qmake project file on GitHub.

The result, if rendered in Ovito, is two silicon atoms (in red) and one oxygen atom:

LAMMPS is a molecular dynamics simulation package that is extremely versatile with plenty of interaction potentials and features implemented. However, you may have written some other code involving atoms and found yourself in the position of considering using a standard file format to write atom data to file. In this case, the XYZ-format has likely passed your mind, but because this is a ASCII-based text format, it is slow to read and write. This format also lacks standardized headers for information such as the system boundaries – causing visualizers like Ovito to have to guess for the right boundaries in your system.

sudo apt-add-repository ppa:comp-phys/stable
sudo apt-get install ovito