Make groups dynamic

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1

Dear colleagues!

I have tried to examine new option to the group command - make groups dynamic. Apparently I did not understand the description of this new option. My script is very simple:

2

Dear colleagues!

I have tried to examine new option to the group command - make groups
dynamic. Apparently I did not understand the description of this new
option. My script is very simple:
------------------------------------------------------------------------------------
# 3d Lennard-Jones melt

units lj
atom_style atomic

lattice fcc 0.8442
region box block 0 10 0 20 0 10
create_box 1 box
create_atoms 1 box
mass 1 1.0
velocity all create 3.0 87287

#Created orthogonal box = (0 0 0) to (16.796 33.5919 16.796)
region liqreg1 block INF INF INF 16.79595 INF INF units box
region liqreg2 block INF INF 16.79595 INF INF INF units box

group liq1 dynamic all region liqreg1 every 1
group liq2 dynamic all region liqreg2 every 1

group liqstat1 region liqreg1
group liqstat2 region liqreg2

pair_style lj/cut 2.5
pair_coeff * * 1.0 1.0 2.5
neighbor 0.3 bin
neigh_modify every 20 delay 0 check no

fix 1 all nve
dump id all atom 50 dump.melt

thermo 50
run 2500
------------------------------------------------------------------------------------
After calculating the log file (log.lammps) contains lines:

group liq1 dynamic all region liqreg1 every 1
0 atoms in group liq1
group liq2 dynamic all region liqreg2 every 1
0 atoms in group liq2

group liqstat1 region liqreg1
4000 atoms in group liqstat1
group liqstat2 region liqreg2
4000 atoms in group liqstat2

And I can not understand why dynamic groups contains
0 atoms, but the static groups - 4000 atoms?
I am using LAMMPS (6 Mar 2014-ICMS).
Could anyone comment on this?

please insert the following lines into your script right before
"thermo 50" and you will see that your groups *do* contain atoms and
*are* dynamic. :wink:

variable num1 equal count(liq1)
variable num2 equal count(liq2)

thermo_style custom step temp v_num1 v_num2

3

Great - it worked!
Axel, Thanks a lot!

Regards,
Vitaly

12.03.2014 23:31, Axel Kohlmeyer ???: