Thank you very much for information. There is the package for smoothed particle hydrodynamics (SPH) in LAMMPS. There is also the molecular dynamics (MD) package in LAMMPS. However, I do not know how to couple these two packages to perform a hybrid SPH/MD simulation. Maybe someone knows?
If there is no explanation in the available documentation, you should contact the authors of the publication. Everything that is available in LAMMPS is mentioned in the documentation. Thus, if the study uses features available in the LAMMPS distribution, they are documented. Otherwise, you need to get them from the author or implement them yourself.