# Energy breakdown and pair interactions **URL:** \ **Category:** User discussions\ **Created:** [February 22, 2021, 11:53am UTC](https://gromacs.bioexcel.eu/t/energy-breakdown-and-pair-interactions/1629 "2021-02-22T11:53:06Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![juanjogf](https://avatars.discourse-cdn.com/v4/letter/j/e95f7d/32.png) [@juanjogf](https://gromacs.bioexcel.eu/u/juanjogf)\ **Post date:** [February 22, 2021, 11:53am UTC](https://gromacs.bioexcel.eu/t/energy-breakdown-and-pair-interactions/1629/1 "2021-02-22T11:53:06Z")
GROMACS version: No GROMACS modification: No Dear Justin and GROMACS buffs, I am trying to obtain energetics contributions of the several parts implied in a protein system simulated but also the atom-pair contributions of each. Of course, I already obtained the individual total contributions for LJ, and Coul, I mean 1-4, SR, Coul-Recip (Long Range I mean) for the three pair-entities: Protein-Protein, Protein-nonProtein and nonProtein-nonProtein. However, I would like also to break down the term Coul-recip associate to PME. I’ve read in the forum by Justin that this is not possible, is it still not possible? ## On the other hand, I’ve obtained the following information from the grompp preprocessing in my system: Generated 20910 of the 20910 non-bonded parameter combinations Generating 1-4 interactions: fudge = 1 Generated 17803 of the 20910 1-4 parameter combinations Excluding 3 bonded neighbours molecule type ‘Protein\_chain\_C’ Excluding 2 bonded neighbours molecule type ‘SOL’ Excluding 1 bonded neighbours molecule type ‘CL’ processing coordinates… ## Making dummy/rest group for Acceleration containing 193475 elements Making dummy/rest group for Freeze containing 193475 elements Making dummy/rest group for VCM containing 193475 elements Number of degrees of freedom in T-Coupling group Protein is 4273.97 Number of degrees of freedom in T-Coupling group non-Protein is 383544.03 One question is, if the 20910 non-bonded parameter combinations shown for my solvated protein system (1705 Protein atoms and 191770 non-Protein atoms) refer here just to those non-bonded pair interactions below the established cutoffs, I mean, if they are only Short Range Interactions, right? …otherwise I cannot understand why so few non-bonded pair-interactions obtained with such a large number of atoms. And finally, can you please tell me if there is any relationship between the number of degrees of freedom in T-Coupling groups (Protein and nonProtein) and the PP and nPnP pair-interactions, respectively, in the whole system? Appreciate a lot your Help!!! JJ