Appending multiple MSD results

I am running a mixture where I am calculating MSD for each molecule type. I plan on running four 2-ns runs instead of one long 8 ns runs. Since the compute msd command initializes the MSD to zero, is it possible to append these four MSD outputs together by offsetting the MSD of each run with the last value of the previous MSD?

I am using the commands:

compute mychunk all chunk/atom molecule

compute MSD all msd/chunk mychunk

fix storeMSD all ave/time 1000 1 1000 c_MSD mode vector file msd.data

In other words, is it okay to average the MSD of the different chunks and use the MSD at the last step as the offset for the next run?

Thank you

I am running a mixture where I am calculating MSD for each molecule type. I
plan on running four 2-ns runs instead of one long 8 ns runs. Since the
compute msd command initializes the MSD to zero, is it possible to append
these four MSD outputs together by offsetting the MSD of each run with the
last value of the previous MSD?

compute msd/chunk is restartable. please see the corresponding note in
the documentation about using the exact same compute id when
restarting.

I am using the commands:

compute mychunk all chunk/atom molecule

compute MSD all msd/chunk mychunk

fix storeMSD all ave/time 1000 1 1000 c_MSD mode vector file msd.data

In other words, is it okay to average the MSD of the different chunks and
use the MSD at the last step as the offset for the next run?

yes. if the compute is properly restarted. i suggest you set up a
small test system to make certain you do it correctly before using it
in a production run.

axel.