(no subject)

hello everyone,

I want to calculate mean-squared displacement (MSD) for multiple chunks of atoms

but when i try to use the following command ,it gives me error ERROR: Unknown compute style (…/modify.cpp:986)

and i am using lammps-30july2016

can anyone help me??

compute cc1 water chunk/atom molecule

compute myChunk water com/msd cc1
fix 1 water ave/time 100 1 100 c_myChunk[*] file tmp.out mode vector