problems with fix bond/create for cross linking polymer systems

LAMMPS LAMMPS Mailing List Mirror
1

Hi all,

I am trying to crosslink bead-spring polymer system using fix bond/create.

I have generated polymer melt using self avoiding random walk and equilibrated it.
I saved the data file and update the header to have

“"
2000 atoms
1 atom types
1980 bonds
1 bond types
4 extra bond per atom
“"

Now I am trying to crosslink it using

special_bonds lj 0 0 1 extra 10

fix crosslink all bond/create 10 1 1 0.7 1 prob 0.1 12321 iparam 3 1 jparam 3 1

I put "special_bonds lj 0 0 1 extra 10” to make it work.

If I put number say 5 it will give me : “ERROR on proc 0: Special list size exceeded in fix bond/create”

I feel very silly but I am failing to understand how can I estimate this number 10 a-priori?

Thank you for you help in advance,
Vasilii.

2

Hi all,

I am trying to crosslink bead-spring polymer system using fix bond/create.

I have generated polymer melt using self avoiding random walk and
equilibrated it.
I saved the data file and update the header to have

“"
2000 atoms
1 atom types
1980 bonds
1 bond types
4 extra bond per atom
“"

Now I am trying to crosslink it using

special_bonds lj 0 0 1 extra 10
fix crosslink all bond/create 10 1 1 0.7 1 prob 0.1 12321 iparam 3 1 jparam
3 1

I put "special_bonds lj 0 0 1 extra 10” to make it work.

If I put number say 5 it will give me : "ERROR on proc 0: Special list size
exceeded in fix bond/create"

I feel very silly but I am failing to understand how can I estimate this
number 10 a-priori?

you cannot. it depends on many factors. you can estimate the upper
limit, though:

at 4 (extra) bonds per atom, you can have 4 more 1-2 neighbors, 4*3=12
more 1-3 neighbors, and 12*3=36 1-4 neighbors for a total of 52.
in practice it will be (much) less, but it should not be more.

axel.

3

Thank you Axel!