[lammps-users] center of mass velocity

hi all
i am trying to find out the viscosity of bulk water using green kubo
formalism. for predicting the axial self diffusion coefficient by the
Geen-Kubo linear response relation we require the axial center of mass
velocity of each molecule. can you suggest me a method to calculate
the center of mass velocity of each molecule in LAMMPS.
looking forward for your valuable suggestions...

There's a compute com/molecule command and a compute atom/molecule
command. The latter can be used with a formula in a variable that you
where you might be able to sum the velocities of atoms in each molecule
and suitably weight them to get Vcm.