Your question is too vague to give a specific answer. Here are three general things to consider:
are you talking about a specific potential function or a specific parameterization of a “known” functional form (like tersoff or lennard-jones)
all features in LAMMPS are documented. You can see the list of supported pairwise potential functions implemented in the command overview tables and the pair style docs. You can go through the lists and compare the docs for the individual styles with the description of the potential (parameters) you are looking for.
LAMMPS bundles only a small subset of the available parameter sets in its “potentials” folder. For the majority of potentials it is necessary to either generate the file yourself or enter the parameters via pair_coeff commands or equivalent (after unit conversion, if needed).
The Feuston and Garofalini potential is an specific potential function, it is a 3-body potential in order to consider the covalent binding. The reference is the following:
J. Chem Phys. 89 (1988) 5818
Several year ago, I made MD simulation using this potential but with the code MDCASK (F.Mota Journal of Nuclear Materials 386–388 (2009) 75–78 ).
Currently, I am going to try to come back to perform MD simulation in silica and I would like to use LAMMPs code to do it. Because it is very stable code and the best option currently under my point of view. However, as it is my first time in using LAMMPS code I do not know how to implement this potential.
Could you give me an idea how to programme potential function in LAMMPS code?
You best start by studying an implementation of a similar manybody potential. Some general instructions for modifying LAMMPS are given in the LAMMPS manual.
Thank you very much for your suggestion Alex. I will continue studying the manual.
But, I am going to try to explain better my first motivation to send this comment in this forum, and sorry for the misunderstanding. What I would like to figure out is whether anyone previously had worked with the interatomic potential Feuston and Garofalini in LAMMPS for amorphous silica, with the aim do not repeat efforts.
I found that several years ago this issue was published in this forum, someone was looking for help for this potential. For this reason, I wondered whether this potential was already implemented in this code.
If anyone has worked with this potential with LAMMPS, I would be very grateful to contact him/her.
What is implemented in the LAMMPS distribution is documented. If it doesn’t show up in the manual, it is not available (as part of the standard LAMMPS distribution)
LAMMPS is quite easy to modify, so people do that for their own purposes and many do submit their changes to be included in the distribution (and to have their well deserved 15 mins of fame). But also a lot of people don’t and there are too many different reasons for that to list them all.
The presence of LAMMPS in this forum is rather new and I don’t know how many people are following the discussions here (yet), perhaps a few 10s. The lammps-users mailing list has currently over 1400 subscribers. So posting to the mailing list will probably increase your chances to get a response (at least for now. we hope that in a few months that may change).
The chances to get a response to questions of the kind “does anybody have a potential for XXX” are generally rather small. People that are willing to share their efforts usually contribute their code to the LAMMPS distribution. Others don’t seem to be too eager to respond (unless they need help themselves). My expectation would be that if you contact the people that have looked for or experimented with the specific potential in the past and most likely to respond, if you contact them directly (provided, that you can read or reconstruct their e-mail addresses).
Thank you very much Alex. I totally agree with you
In the main time I figure out the way to implement this potential I will send the answer in the lammps-user mailing, in order to try to find someone who has used this potential in lammps, as you have recomended. Because, I though that this Forum and the lammps-user mailing were the same, but clearly, I were wrong
The forum archives the mailing list, but there is no way to send the forum messages to the mailing list.
Using the forum is an experiment to see if this format can improve the user support.
The mailing list has a few problems:
people have a tendency to respond to people individually and not to the mailing list, so discussions and especially their resolutions may not be seen by others
unless you store all mailing list emails in a folder of your own, searching of old emails requires to go to the archive and there is no easy way to follow up on that
there is a significant number of off-topic questions
availability, reliability and performance of the sourceforge mailing list have had occasional issues of the last couple of years
With using the forum we hope to address these issues as all conversations stay on the same locations, are available for searches even if you joined later, topics can be recategorized to one of the other forums on the same server and the server is not used by as large a number of users as the sourceforge facility. But since this is early in the transition, it is not clear whether the LAMMPS user community is willing to make the transition or prefers to live with the old system of communication.