Question about a fixed bond lenght

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1

Hi,

I am working with LAMMPS 2001 (Fortran version) and I was wondering if there is any way to define a fixed bond length via the input file.
I am trying to introduce a cluster of atoms inside a domain filled with simple Lennard-Jones fluid. the cluster would have a specific shape that would retain its through out the simulation. the cluster would interact with other atoms in the domain via Lennard-Jones interaction.
I have tried to use harmonic bond between the atoms in the cluster with high constant but that was not successful. If you have any suggestion that would be very appreciated
thanks,

2

Hi,

I am working with LAMMPS 2001 (Fortran version) and I was wondering if there
is any way to define a fixed bond length via the input file.
I am trying to introduce a cluster of atoms inside a domain filled with
simple Lennard-Jones fluid. the cluster would have a specific shape that
would retain its through out the simulation. the cluster would interact with
other atoms in the domain via Lennard-Jones interaction.
I have tried to use harmonic bond between the atoms in the cluster with high
constant but that was not successful. If you have any suggestion that would
be very appreciated

the Fortran version of LAMMPS has been obsolete for a very long time.
the C++ version offers a collection of "fix rigid" integrators that
provide the function that you seem to be looking for.
you either need to switch or give yourself a helping hand.

axel.

3

Thanks for your answer.
The reason that I am sticking with the old version is because of my own implementation in the original code. migrating to C++ version is very painful at this stage. is there an other solution rather that switching to C++ version. any suggestion where (which subroutines) to write my own fix rigid in fortran version?
thanks

4

Thanks for your answer.
The reason that I am sticking with the old version is because of my own
implementation in the original code. migrating to C++ version is very
painful at this stage. is there an other solution rather that switching to
C++ version.

you have put yourself between a rock and a hard place by working with
the fortran version.

any suggestion where (which subroutines) to write my own fix
rigid in fortran version?

i haven't looked at it for at least 5 years, and even then didn't look
to closely. if you want to stick with the fortran version, you are own
your own. i doubt that there is anybody else around that still wants
to invest any serious effort into it.

life is tough,
    axel.

5

The Fortran version has a shake command, which
constrains bonds. I'd look at that if you want
something related, but different.

Steve