Hi all

Could someone help me, I performed NVT run for an amorphous cell containig of polymer and 5 gas molecules, and then I created a set of gas molecules to calculate MSD .  I m interested in knowing how Material Studio calculates MSD for a set which contains more than one molecule, whether it firstly calculates center of mass of this set and then calculates MSD for this point or it calculates MSD for each gas molecule and then performs averaging over gas molecules .

Thanks in advance!

nima