"fix bond/break" or how to delete a specified bond

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1

Dear Lammps Users,

I have a question for breaking a bond. There are commands “fix bond/break” and “delete_bonds”. However, both two commands only use bond type as a condition (argument) in order to break bonds.

For example, “fix 5 all bond/break 10 2 1.2” means that all bond types 2 will break if bond length is longer than 1.2 (based on units anyway) every 10 timesteps during a simulation.

Likewise, “delete_bonds” command also uses bond type for “style bond” arguments. I have not found any commands to solve this problem.

However, I do not want to use all 2 type bonds. I only break bonds between specified atoms. I mean, for example, that a bond between atom number 20 and atom number 367 and a bond between atom number 283 and atom number 1386, etc will break.

Does Lammps be able to do this?

Any comments are appreciated.

Thanks in advance.

Best regards,
Changwoon Jang

2

Dear Lammps Users,

I am sorry to complicate you from the sentence, “Likewise ~~” in the previous mail. My question is,

I have a question for breaking a bond. There are commands “fix bond/break” and “delete_bonds”. However, both two commands only use bond type as a condition (argument) in order to break bonds.

For example, “fix 5 all bond/break 10 2 1.2” means that all bond types 2 will break if bond length is longer than 1.2 (based on units anyway) every 10 timesteps during a simulation.

Likewise, “delete_bonds” command also uses bond type for “style bond” arguments.

However, I do not want to use all 2 type bonds. I only break bonds between specified atoms. I mean, for example, that a bond between atom number 20 and atom number 367 and a bond between atom number 283 and atom number 1386, etc will break.

I have not found any lammps commands to solve this problem.

Does Lammps be able to do this?

Any comments are appreciated.

3

Dear Lammps Users,

    I have a question for breaking a bond. There are commands "fix
bond/break" and "delete_bonds". However, both two commands only use bond
type as a condition (argument) in order to break bonds.

For example, "fix 5 all bond/break 10 2 1.2" means that all bond types 2
will break if bond length is longer than 1.2 (based on units anyway) every
10 timesteps during a simulation.

Likewise, "delete_bonds" command also uses bond type for "style bond"
arguments. I have not found any commands to solve this problem.

However, I do not want to use all 2 type bonds. I only break bonds between
specified atoms. I mean, for example, that a bond between atom number 20 and
atom number 367 and a bond between atom number 283 and atom number 1386, etc
will break.

Does Lammps be able to do this?

sure. just give those bonds a new type and copy over the parameters
from the old bond type.

axel.

4

Dear Axel,

I got it. IT’S SIMPLE.

Thanks again and sorry for your name (Alex) in the reply to you.

Best regards,
Changwoon Jang

5

Dear Axel,

I got it. IT'S SIMPLE.

yup. all problems are simple, once you look
at them from the right angle. :wink:

Thanks again and sorry for your name (Alex) in the reply to you.

no problem. i am used to it. about a quarter or so
of the people that e-mail me, don't notice or know
the difference. most of the time i don't even notice it.