Problem calculating density with ave/chunk

LAMMPS LAMMPS General Discussion
1

Dear Lammps Users,

I’m simulating a droplet of water on silica, and I have used a combination of NVE for water, and NVT for silica.

I want to measure the contact angle, to do that I used a compute chunk/atom and a fix ave/chunk, but the output files only have these lines.

# Chunk-averaged data for fix dens_bin and group all

# Timestep Number-of-chunks Total-count
# Chunk Coord1 Coord2 Ncount density/mass

I used this lines to compute the density in bins and the temperature, but in both cases, the output was the same. My idea is to collect data every 500 fs and ponderate 20 values every 10.000 fs.

compute bins_dens all chunk/atom bin/2d y center 1.13333 z center 1.13333 compress no bound y 20 400 bound z 60 190
compute bins_temp all chunk/atom bin/2d y center 1.13333 z center 1.13333 compress no bound y 20 400 bound z 60 190

fix dens_bin all ave/chunk 500 20 10000 bins_dens density/mass file dens.data
fix temp_bin all ave/chunk 500 20 10000 bins_temp temp ave running file temp.data

Does anyone know what is happening here?

2

What LAMMPS version is this with?

3

The problem is probably your use of the reset_timestep command. It should come directly after read_restart.

Say your restart was written at timestep 2000000.
Then you have the fix ave/chunk commands and they will be set up to produce the next output on step 2010000. But then you do a reset_timestep 0 and a run 500000 so you will not reach that timestep for creating output. With a recent LAMMPS version the reset_timestep command would trigger an error.