LAMMPS Improvement for Active Matter Research

Hello sir

i want to discuss one thing here …

The Lammps in Active matter matter research where pair wise interactions are very important is useful. But very few potentials that use raduis from atom style ,like yukawa/ colloid are present in lammps. Harmonic potential is present in lammps but it is not useful radius dependent of particles… U=-k(rc-rij)^2

i want to use harmonic potential that have been used in many papers as radius dependent.

Harmonic potential U = -k[(Ri+Rj)−rij ]^2 Θ[(Ri+Rj)−rij), where Ri and Rj are the radii of two interacting particles, rij=ri-rj , Θ is the unitary step function.

How i can get help to implement this potential?

  1. Is there any possibility in pair_style table which can support radius changes?

  2. can LAMMPS developers help for this potential including in Lammps?

  3. Or developers Emails contact where we can contact for this problem.

It must be usefull for Active Matter researcher.

As should be very obvious from the documentation: no.

If you want to implement a custom potential, you can write your own. The LAMMPS manual has detailed explanations on how to modify LAMMPS for your personal needs. Please note that a very large part of LAMMPS has been programmed by people like you that had a specific need, implemented that model for their research and then were generous enough to share it with the LAMMPS community to contribute their implementation for inclusion into the LAMMPS distribution.

If you want to request a feature to be implemented in LAMMPS you can submit a feature request issue on GitHub. If you would email any of the core LAMMPS developers personally they will tell you the same or point you to the section of the manual on modifying LAMMPS. But please don’t get your hope up, since there are quite a large number of feature requests and the core LAMMPS developers have their own projects that they are working on.

One thing that I personally consider very off-putting in your post (and you are not the first person to act like this) is to not be honest about the purpose. Why not just say that this is extremely important for you personally? Why make look like you are acting for the benefit of others? If there were so many others that are in need of this feature, it would very likely have been implemented already. This is doubly true for the case that you are quoting, since this is a rather minor modification and thus the implementation of a pair style harmonic/sphere should be rather straightforward based on the information already provided in the LAMMPS documentation.

For me personally, that way of asking for a feature instantly kills any desire to help. But there are still plenty of other people reading posts here and many of those have the (rather basic) C++ programming skills required to implement such a feature in LAMMPS. Perhaps one of them (still) feels like helping you out…

Thanks Sir for your breif and informative reply.

sorry i bothered LAMMPS community.

i tried it and discussed it with some C++ programmers… but failed then i posted here…

Harmoniccut.cpp , Modyfying file how i can use in my script?

what command needed like pair_style ?

I already pointed out the relevant sections in the LAMMPS manual. Short of doing your work for you there is not much else I can do or recommend beyond what I already did.