[lammps-users] volume unit

In the units section, real units have grams/mole for mass and angstroms for distance. In that case density should be in grams/angstroms cube.

For granular atom styles, the density for atoms gets very small in that case. How do we enter this small number. Is there any option to enter in scientific format? I tried to enter in g/cm cube just to see if I can run granular style. It gave segmentation fault. I am thinking the big density values I entered may be the reason. I did not try writing 24 decimal digits!


Hi Burcu. Why are you using real units with atom style
granular. I think you want lj units. See this example:

# LAMMPS benchmark of granular flow
# chute flow of 32000 atoms with frozen base at 26
units lj
atom_style granular
boundary p p fs
newton off
read_data data.chute
pair_style gran/history 200000.0 50.0 0.5 0
neighbor 0.1 bin
neigh_modify every 1 delay 0
timestep 0.0001
group bottom type 2
group active subtract all bottom
neigh_modify exclude group bottom bottom
fix 1 all gravity chute 26.0
fix 2 bottom freeze
fix 3 active nve/gran
thermo_style granular
thermo 100
run 100

For real units, densities should be in units of
gm/(mol*angs^3). So the density magnitudes in a
typical simulation will be on the order of 1.0

You can use scientific notation in the LAMMPS input
scripts: 1e-4 works just as well as 0.0001.

I hope this helps!