I am using the fix deposit command to add atoms to my structure like this:
pair_style reax/c/omp control
pair_coeff * * ffield_CHOWaterAlSiFe C Si O
fix 3 all nvt temp 1600.0 1600.0 0.005
fix o2_deposit all deposit 6 0 100 12345 region dep_region vz 0.0 -10.0 mol o2_molecule near 5.0
They are added to all, nvt also acts on all. So I would expect all the atoms to move. However, this is not the case. Is there something I am missing?
Thank you!
How did you determine this velocity? This seems about a 1000 times larger than typical atom velocities for build systems in real units, and thus more like velocities for metal units.
Since you don’t provide a complete input deck, it is very difficult to make any specific assessments. The fact that you are using pair_style reax/c/omp also indicates that you are using an old LAMMPS version and should update to the latest version (where you need to use reaxff/omp or just plain reaxff and the -suffix omp flags on the command line).
[Update:]
I just created a small test job based on one of the ReaxFF examples and there is no problem with having deposited atom move. Of course due to the extremely high velocity, each deposited atom causes quite a bit of a spike in the temperature. 
Thank you very much for your response! It’s working now.