Only inserted 595 particles out of 2000

LAMMPS LAMMPS Beginners
, ,
1

Dear everyone，
I am trying to insert 2000 O2 molecules around a relaxed cu nanoparticle in the simulation box，but I get a WARNING: Only inserted 595 particles out of 2000 (…/create_atoms.cpp:855) Created 1190 atoms. Why only 595 particles instead of all of them was inserted?How can I do some modification?Thanks a lot!
Here is my input file:

units real
dimension 3
boundary p p p
atom_style full
neighbor 0.5 bin
neigh_modify every 5 delay 0 check yes

pair_style reaxff lmp_control safezone 2.5 mincap 3000

region box block 0 200 0 200 0 200 units box
create_box 2 box

mass 1 16.00
mass 2 63.55

region cunp sphere 100 100 100 12 side in units box
lattice fcc 3.61
create_atoms 2 region cunp

pair_coeff * * CuOH.ff O Cu

group cu type 2

#cu relax

fix 1 all qeq/reax 10 0.0 10.0 1e-6 reax/c

min_style cg
minimize 1.0e-6 1.0e-8 1000 10000

timestep 0.5
fix relax cu npt temp 300.0 300.0 100.0 iso 1.0 1.0 1000 drag 0.1

thermo 100
thermo_style custom step temp pe
run 80000

region oxygen sphere 100 100 100 15 side out
molecule O2 O2.data
create_atoms 0 random 2000 20010 oxygen mol O2 25367 overlap 1.5

write_data 300k2000.data

2

The create_atoms command has a maxtry keyword that may interest you. From the create_atoms page:

maxtry value = Ntry
    Ntry = number of attempts to insert a particle before failure

Best,
Simon

3

Because there were too many overlaps. The create_atoms command places molecules at random locations with random orientations. With that approach, you can only reach a certain density until many attempts to insert molecules will fail. If you want to insert more molecules, you need to use a larger region or do the insertion in multiple steps with some MD steps in between so that the molecules can relax and become more compact and thus have larger voids in the region.