shock-wave binning

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#1

I am running a shock simulation and am trying to reproduce some methodology in a paper: Molecular dynamics simulations of shock waves in oriented nitromethane single crystals

I would like to calculate the com and bin them in order to keep track of the velocity of the shocked wave. Now I am running into some trouble converting the ave/spatial command to the chunk/atom fix and compute.

My command is this:

fix com_prof all ave/spatial 10 5 100 z lower ${delta} c_MYcom[3] file com.profle units box

Now I would like to convert this because LAMMPS no longer accepts this format.

My attempt at this is:

compute cc1 all chunk/atom bin/1d z lower ${delta}
fix 1 all ave/chunk 10 5 100 c_MYcom[3] file vel.profile

Can anyone confirm whether I have properly adjusted this?

Jackson
#2

Sorry I should have been clearer. This does not work. I get that I have no values in fix/ave chunk command, but I cannot figure out why.

#3

Sorry for all the updates - I realized I forgot the cc1 (duh). I still get that ave/chunk does not calc per atom values. This confuses me, I thought the whole point was to average per atom values?

#4

If you average atom quantities into 10 spatial bins, then the

output is 10 values, not N values for N atoms. So the output

of fix ave/chunk is “global” in LAMMPS lingo, the # of chunks.

Compute chunk/atom produces a per-atom value which is

the chunk ID each atom is assigned to.

You can also look at fix ave/atom which produces per-atom

averages (for each atom).

Steve