[lammps-users] Question on fix recenter and multiple fix msds

Sorry, hit send accidentally. Continuing,

So the question is, what is the correct way of doing what I want? Would

fix 3 all msd 100 diffsquared.1 com yes
run 250000

fix 4 all msd 100 diffsquared.2 com yes
run 250000

work? I assume I have to get rid of the fix recenter, but not fixes 3 and 4 will each subtract out the COM motion relative to the time they were called. Then, if I have to remove the COM motion for other data analysis, I can always do it in postprocessing rather than the fix recenter. Should this be OK? Are there any other issues with msd fixes at multiple time origins (and multiple “run” commands) I should know about?


Your latter example with 2 msd fixes, each with com yes should work
as you expect. For many time windows, post-processing is best.