Mean square displacement

Hi everyone,

I'm using Materials Studio to analyze mean square displacement (MSD) data for self-diffusion studies. I understand that the MSD is typically calculated using the displacement of particles over time, but I’d like to confirm the best practice:

Is self-diffusion analysis in Materials Studio generally performed on a specifically defined set, or is it computed over the entire simulation system? Any insights or examples from your experience would be greatly appreciated.

Thanks in advance!