1-5 interactions source code

Dear LAMMPS Developers/Users

I am trying to simulate multiple long chain molecules with 8 atom types (approximately 1000 beads per chain). I want to include 1-5 and 1-6 interactions. I have gone through a lot of previous threads on the same topic. One of the threads I ended up was one with Andrew Jewett, who was kind enough to give detailed explanations for incorporating this:

Topic 1 of https://sourceforge.net/p/lammps/mailman/message/29508433/
Last topic in https://lammps.sandia.gov/threads/msg29789.html

However, (I presume that) the codes wherein the user can input the inter and intramolecular parameters are not included in current LAMMPS version (if so it would be great if someone can point me to that) - I want to use an r-dependent lj96/cut potential for the 1-5 interactions in addition to the normal 1-5 non-bonded potential.

In the thread Andrew points to a page where more details regarding the changes to the code that need to be made are given (http://lammps.sandia.gov/threads/msg24134.html). However, the link points to a page which unfortunately has nothing to do with 1-5 interactions. It would be great if someone can point to a page where I can start. Axel had suggested to start looking at neighbor list codes(https://lammps.sandia.gov/threads/msg29779.html). Before doing it, I just wanted to make sure, I am not exhausting all easier options.

Thanks in advance

Vaidyanathan M S
Postdoctoral Fellow
Department of Chemical Engineering and Materials Science
University of Minnesota Twin Cities

Dear LAMMPS Developers/Users

I am trying to simulate multiple long chain molecules with 8 atom types (approximately 1000 beads per chain). I want to include 1-5 and 1-6 interactions. I have gone through a lot of previous threads on the same topic. One of the threads I ended up was one with Andrew Jewett, who was kind enough to give detailed explanations for incorporating this:

Topic 1 of https://sourceforge.net/p/lammps/mailman/message/29508433/
Last topic in https://lammps.sandia.gov/threads/msg29789.html

However, (I presume that) the codes wherein the user can input the inter and intramolecular parameters are not included in current LAMMPS version (if so it would be great if someone can point me to that) - I want to use an r-dependent lj96/cut potential for the 1-5 interactions in addition to the normal 1-5 non-bonded potential.

please see fix cmap for a potential that spans more than 4 atoms, and that does not require and changes to the neighbor list exclusions (same as your model). it shows how to store relevant topology information in the data file, that is used by a fix instead of any standard force interaction. it should be straightforward to apply this to 1-5 pair and 1-6 pairs (to be used with a second fix).

In the thread Andrew points to a page where more details regarding the changes to the code that need to be made are given (http://lammps.sandia.gov/threads/msg24134.html). However, the link points to a page which unfortunately has nothing to do with 1-5 interactions. It would be great if someone can point to a page where I can start. Axel had suggested to start looking at neighbor list codes(https://lammps.sandia.gov/threads/msg29779.html). Before doing it, I just wanted to make sure, I am not exhausting all easier options.

(massive) changes to the neighbor list code would only be required for models where the non-bonded interactions for the pairs should be removed from the neighbor list. this doesn’t seem to be the case here.

axel.