reg: one or more keywords in fix bond/create

Hello lammps users, I have two questions regarding the fix bond create command in lammps

  1. What is the use of one or more keywords in fix bond/create command ? or in which case will this be useful ? For example
fix 5 all bond/create 1 3 3 0.8 1 prob 0.5 85784 iparam 2 3 iparam 2 4 ??

Thanks
Arun 

Hello lammps users, I have two questions regarding the fix bond create
command in lammps

1. What is the use of one or more keywords in fix bond/create command ? or
in which case will this be useful ? For example

fix 5 all bond/create 1 3 3 0.8 1 prob 0.5 85784 iparam 2 3 iparam 2 4 ??

http://lammps.sandia.gov/doc/fix_bond_create.html

Ok got it.

Is the maxbond criteria guaranteed to work with multiple fix bond/create ?. I have the following in my code.

fix 1r all bond/create 1 14 15 14 235 iparam 1 20 jparam 1 17 prob 1 4546
fix 2r all bond/create 1 14 17 14 235 iparam 1 20 jparam 1 18 prob 1 4546
fix 3r all bond/create 1 14 16 14 235 iparam 1 20 jparam 1 19 prob 1 4546
run 3

In my simulation none of the atom types above have the bond of bondtype 235 to begin with.
So after the first run command, the atom type changes to 17 from 15 (assume a bond is formed in the first run).
Now 17th atom type has a bond of 235. In the second run, the 17 the atom type should not form a bond with atom type 14 since it already has maxbonds which is 1. But it is forming a bond in my simulation.

I am not able to interpret the maxbond criteria correctly.

Dr. Axel can you please explain.

Ok got it.

Is the maxbond criteria guaranteed to work with multiple fix bond/create ?.
I have the following in my code.

fix 1r all bond/create 1 14 15 14 235 iparam 1 20 jparam 1 17 prob 1 4546
fix 2r all bond/create 1 14 17 14 235 iparam 1 20 jparam 1 18 prob 1 4546
fix 3r all bond/create 1 14 16 14 235 iparam 1 20 jparam 1 19 prob 1 4546
run 3

In my simulation none of the atom types above have the bond of bondtype 235
to begin with.
So after the first run command, the atom type changes to 17 from 15 (assume
a bond is formed in the first run).
Now 17th atom type has a bond of 235. In the second run, the 17 the atom
type should not form a bond with atom type 14 since it already has maxbonds
which is 1. But it is forming a bond in my simulation.

I am not able to interpret the maxbond criteria correctly.

maxbond does what the documentation says, no more, no less. and you
are asking fix bond/create do so something that is ambiguous, so there
is always an opportunity for a race condition. if an atom of type 14
is within 14 length units of multiple atoms of types 15, 16, or 17,
which one should "win"? why not process all three bond/create fixes in
separate runs? it looks as if you are trying to use the command for
topology building and not exactly for the purpose that it was
originally intended for.

axel.