How to print wall-grain interaction parameters in granular package

Dear all,
I am very new to the LAMMPS but have experience in MD simulations.

I am using Granular package in LAMMPS and I am using a 2D granular system bounded in Y-directions by the Y-Walls (Horizontal wall) and the wall-grain interaction is of “hertz/history”. The code is working fine and giving me correct results.

For grain-wall interaction, I am using the following command:

fix ylower all wall/gran hertz/history {Kn} {Kt} {Gamman} {Gammat} {xmu} {dampflag} yplane -1.0 10.0

However, I would like to print the details of Grain-wall interaction parameters. For example, at any timestep, I would like to print seven columns like “index dnX dnY dnZ dsX dsY dsZ”, where dn is the overlap of the particle with the wall surface and ds is the tangential distance from the walls.

My questions: Can anyone kindly advise me how can I print the grain-wall interaction parameters with time in a file.

Dear all,
              I am very new to the LAMMPS but have experience in MD simulations.

I am using Granular package in LAMMPS and I am using a 2D granular system bounded in Y-directions by the Y-Walls (Horizontal wall) and the wall-grain interaction is of "hertz/history". The code is working fine and giving me correct results.
For grain-wall interaction, I am using the following command:

fix ylower all wall/gran hertz/history \{Kn\} {Kt} \{Gamman\} {Gammat} \{xmu\} {dampflag} yplane -1.0 10.0

However, I would like to print the details of Grain-wall interaction parameters. For example, at any timestep, I would like to print seven columns like "index dnX dnY dnZ dsX dsY dsZ", where dn is the overlap of the particle with the wall surface and ds is the tangential distance from the walls.

My questions: Can anyone kindly advise me how can I print the grain-wall interaction parameters with time in a file.

you have to modify the source code.

axel.