# DispCorr parameter in GROMACS for Self Assembled Systems **URL:** \ **Category:** User discussions\ **Created:** [November 2, 2020, 12:03pm UTC](https://gromacs.bioexcel.eu/t/dispcorr-parameter-in-gromacs-for-self-assembled-systems/1035 "2020-11-02T12:03:35Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![tejchoksi](https://avatars.discourse-cdn.com/v4/letter/t/e56c9b/32.png) [@tejchoksi](https://gromacs.bioexcel.eu/u/tejchoksi)\ **Post date:** [November 2, 2020, 12:03pm UTC](https://gromacs.bioexcel.eu/t/dispcorr-parameter-in-gromacs-for-self-assembled-systems/1035/1 "2020-11-02T12:03:35Z")
GROMACS version: 2019.2 GROMACS modification: No Dear GROMACS Users, I had a question regarding the parameter, DispCorr. I am studying the self-assembly of surfactants in water. We anticipate that the surfactants will self-assemble into a mix of micelles and long rod-like aggregates. I am using the CHARMM36 forcefield to describe the surfactant molecules. In the manual, I came across this sentence, “Note that dispersion correction should be applied in the case of lipid monolayers, but not bilayers”. > **[Force fields in GROMACS — GROMACS 2020-beta3 documentation](http://manual.gromacs.org/documentation/2020-beta3/user-guide/force-fields.html)** I also observed that in the nvt.mdp file given for the Protein-Ligand tutorial on ([http://www.mdtutorials.com/gmx/complex/Files/nvt.mdp](http://www.mdtutorials.com/gmx/complex/Files/nvt.mdp)), the comment on DispCorr mentions that no correction is used for a proteins with C36. Since I am studying self-assembly, I initiate my system with randomly distributed surfactant molecules. So, my system does not begin with monolayers or bilayers, nor does it contain proteins. I am confused about what I should be setting DispCorr to. Could you please guide me on whether or not I should be using dispersion correction for my particular system of surfactants in water? Thank you, Sincerely, Tej * * * **Tej S. Choksi** Assistant Professor School of Chemical and Biomedical Engineering Nanyang Technological University, Singapore Block N1.2, B1-18 62 Nanyang Drive Singapore 637459 Office: +65 6316 8940 ---
**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\ **Post date:** [November 2, 2020, 3:04pm UTC](https://gromacs.bioexcel.eu/t/dispcorr-parameter-in-gromacs-for-self-assembled-systems/1035/2 "2020-11-02T15:04:48Z")
The only system type for which one would use dispersion correction with CHARMM36 is a phospholipid monolayer. It should not be used for anything else. The comment in the documentation specifically addresses bilayers vs. monolayers because it is a point of confusion among users, but should perhaps be better phrased that only monolayers require it. Nothing else does. ---
**Author:** ![Masrul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/masrul/32/234_2.png) [@Masrul](https://gromacs.bioexcel.eu/u/Masrul)\ **Post date:** [November 2, 2020, 8:18pm UTC](https://gromacs.bioexcel.eu/t/dispcorr-parameter-in-gromacs-for-self-assembled-systems/1035/3 "2020-11-02T20:18:14Z")
Dr. Lemkul, I have a question regarding this. What if someone uses Dispersion correction incorrectly for CHARMM, what would be consequences as correction term is a constant offset? Regards, Masrul ---
**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\ **Post date:** [November 2, 2020, 8:40pm UTC](https://gromacs.bioexcel.eu/t/dispcorr-parameter-in-gromacs-for-self-assembled-systems/1035/4 "2020-11-02T20:40:21Z")
I think it will depend on the system. For a membrane, in which LJ interactions dominate, you’d probably get systematically too-favorable interactions among the alkyl groups. For a protein or nucleic acid in water, the differences are probably negligible, but I don’t know if anyone has ever looked at that before.