# Adjustment in the mdp files for CHARMM36m **URL:** \ **Category:** User discussions\ **Created:** [November 18, 2020, 7:16pm UTC](https://gromacs.bioexcel.eu/t/adjustment-in-the-mdp-files-for-charmm36m/1114 "2020-11-18T19:16:46Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![lanselibai](https://avatars.discourse-cdn.com/v4/letter/l/e9c0ed/32.png) [@lanselibai](https://gromacs.bioexcel.eu/u/lanselibai)\ **Post date:** [November 18, 2020, 7:16pm UTC](https://gromacs.bioexcel.eu/t/adjustment-in-the-mdp-files-for-charmm36m/1114/1 "2020-11-18T19:16:46Z")
GROMACS version:2020 GROMACS modification: Yes/No Here post your question I want to use the CHARMM36m forcefield. [This website](http://manual.gromacs.org/documentation/2019-rc1/user-guide/force-fields.html) said For using CHARMM36 in GROMACS 5.0 and newer, please use the following settings in the [mdp](http://manual.gromacs.org/documentation/2019-rc1/reference-manual/file-formats.html#mdp) file: constraints = h-bonds cutoff-scheme = Verlet vdwtype = cutoff vdw-modifier = force-switch rlist = 1.2 rvdw = 1.2 rvdw-switch = 1.0 coulombtype = PME rcoulomb = 1.2 DispCorr = no I am following Justin’s lysozyme tutorial, in which the mdp files include ions.mdp minim.mdp nvt.mdp npt.mdp md.mdp My questions are 1. The so-called “use the following settings in the mdp” only refers to the md.mdp file? 2. The Justin’s tutorial uses the OPLS forcefield. To adapt to the CHARMM36m FF, should I simply copy those lines (i.e. constraints = h-bonds, cutoff-scheme, etc.) at the end of his mdp file, so that those parameters will be overwritten? ---
**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 18, 2020, 7:34pm UTC](https://gromacs.bioexcel.eu/t/adjustment-in-the-mdp-files-for-charmm36m/1114/2 "2020-11-18T19:34:49Z")
> [@lanselibai](#): > > The so-called “use the following settings in the mdp” only refers to the md.mdp file? No, everything needs to be done consistently and using the proper settings for the force field, except `ions.mdp`, which is not used for a simulation so its contents are irrelevant. > [@lanselibai](#): > > The Justin’s tutorial uses the OPLS forcefield. To adapt to the CHARMM36m FF, should I simply copy those lines (i.e. constraints = h-bonds, cutoff-scheme, etc.) at the end of his mdp file, so that those parameters will be overwritten? `grompp` will complain about double entries for keywords. Replace the values with proper ones. ---
**Author:** ![Dylansmith](https://avatars.discourse-cdn.com/v4/letter/d/bc79bd/32.png) [@Dylansmith](https://gromacs.bioexcel.eu/u/Dylansmith)\ **Post date:** [August 10, 2021, 5:34pm UTC](https://gromacs.bioexcel.eu/t/adjustment-in-the-mdp-files-for-charmm36m/1114/3 "2021-08-10T17:34:32Z")
Hello Justin, Thanks for your feed,. My question might be … I searched in many publications still have doubts. I have only protein in two separate chains for Gromacs MD simulation with CHARMM36m. What is the best strategy for tcouple and pcouple? I really appreciate your guide here for. Dylan ---
**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:** [August 10, 2021, 5:55pm UTC](https://gromacs.bioexcel.eu/t/adjustment-in-the-mdp-files-for-charmm36m/1114/4 "2021-08-10T17:55:33Z")
> [@Dylansmith](#): > > What is the best strategy for tcouple and pcouple? What do you mean? Algorithms? Assigning `tc-grps`? ---
**Author:** ![Dylansmith](https://avatars.discourse-cdn.com/v4/letter/d/bc79bd/32.png) [@Dylansmith](https://gromacs.bioexcel.eu/u/Dylansmith)\ **Post date:** [August 10, 2021, 6:10pm UTC](https://gromacs.bioexcel.eu/t/adjustment-in-the-mdp-files-for-charmm36m/1114/6 "2021-08-10T18:10:28Z")
Thank you. I mean the thermostat and barostat in the mdp files? . The algorithms ---
**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:** [August 19, 2021, 2:20pm UTC](https://gromacs.bioexcel.eu/t/adjustment-in-the-mdp-files-for-charmm36m/1114/7 "2021-08-19T14:20:58Z")
Anything except the Berendsen weak coupling method is valid. Studies should specifically state what was used in publications. ---
**Author:** ![Dylansmith](https://avatars.discourse-cdn.com/v4/letter/d/bc79bd/32.png) [@Dylansmith](https://gromacs.bioexcel.eu/u/Dylansmith)\ **Post date:** [August 29, 2021, 4:16am UTC](https://gromacs.bioexcel.eu/t/adjustment-in-the-mdp-files-for-charmm36m/1114/8 "2021-08-29T04:16:37Z")
Dear Dr. Lemkul, thank you so much. Well understood.