[lammps-users] Dev: Difference between variables?

Dear Steve and Lammps users,

Can some body tell me the difference between mass and rmass? and when should I use one or the other?

Also, what is the value returned when:

“if (mass)” …, being mass = atom->mass

In fix_thermal_conductivity.cpp it seems that in order to get the mass you need the atom’s type, while to use rmass you can get the value from the local index. I do not understand why the difference?

Thanks in advance, Javier

Different kinds of atom_style particles assign mass differently.
mass is per-type mass. rmass is per-atom mass (like for granular
particles). The doc page for the mass command discusses this,