# How to decouple the Lennard-Jones (LJ) interaction between two particular atoms in a same molecule?

**URL:** <https://gromacs.bioexcel.eu/t/how-to-decouple-the-lennard-jones-lj-interaction-between-two-particular-atoms-in-a-same-molecule/9622>\
**Category:** User discussions\
**Tags:** forcefield, mdp-parameters, free-energy, simulation-setup\
**Created:** [July 11, 2024, 1:16pm UTC](https://gromacs.bioexcel.eu/t/how-to-decouple-the-lennard-jones-lj-interaction-between-two-particular-atoms-in-a-same-molecule/9622 "2024-07-11T13:16:23Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![roshanshrestha](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/roshanshrestha/32/515_2.png) [@roshanshrestha](https://gromacs.bioexcel.eu/u/roshanshrestha)\
**Post date:** [July 11, 2024, 1:16pm UTC](https://gromacs.bioexcel.eu/t/how-to-decouple-the-lennard-jones-lj-interaction-between-two-particular-atoms-in-a-same-molecule/9622/1 "2024-07-11T13:16:23Z")

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GROMACS version: 2023.2  
GROMACS modification: No  
Hi all, I would like to decouple the lennard-jones (LJ) interaction between two coarse-grained (MARTINI) beads of the same molecule. These beads obviously doesn’t have any bonded interactions between them, so only the non-bonded interactions. Is it possible to do that with GROMACS? Here, the whole idea is to decouple the LJ interactions between these two particles over lambda from 0 to 1 at some interval. So, when lambda is equal to 0, there will be a strong LJ interaction, and with the increase in lambda value, the LJ interaction vanishes  
Thanks