# Urgent Help: Error- atoms are not part of any of the T-Coupling groups **URL:** \ **Category:** User discussions\ **Created:** [July 15, 2023, 5:52pm UTC](https://gromacs.bioexcel.eu/t/urgent-help-error-atoms-are-not-part-of-any-of-the-t-coupling-groups/6844 "2023-07-15T17:52:00Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![shanza](https://avatars.discourse-cdn.com/v4/letter/s/4491bb/32.png) [@shanza](https://gromacs.bioexcel.eu/u/shanza)\ **Post date:** [July 15, 2023, 5:52pm UTC](https://gromacs.bioexcel.eu/t/urgent-help-error-atoms-are-not-part-of-any-of-the-t-coupling-groups/6844/1 "2023-07-15T17:52:00Z")
when i run my nvt.mdp file i got the following error Fatal error: 73 atoms are not part of any of the T-Coupling groups what should i do to resolve this ---
**Author:** ![Karis](https://avatars.discourse-cdn.com/v4/letter/k/ed8c4c/32.png) [@Karis](https://gromacs.bioexcel.eu/u/Karis)\ **Post date:** [July 16, 2023, 4:17am UTC](https://gromacs.bioexcel.eu/t/urgent-help-error-atoms-are-not-part-of-any-of-the-t-coupling-groups/6844/2 "2023-07-16T04:17:23Z")
This other post might be helpful > [@How to fix this error which says 59196 atoms are not part of any of the T-coupling group in MD simu](https://gromacs.bioexcel.eu/t/how-to-fix-this-error-which-says-59196-atoms-are-not-part-of-any-of-the-t-coupling-group-in-md-simu/6835): > > GROMACS version: GROMACS modification: Yes/No Here post your question How to fix this error in equilibration steps of MD simulation which says 59196 atoms are not part of any of T-coupling groups ? ---
**Author:** ![shanza](https://avatars.discourse-cdn.com/v4/letter/s/4491bb/32.png) [@shanza](https://gromacs.bioexcel.eu/u/shanza)\ **Post date:** [July 16, 2023, 7:15am UTC](https://gromacs.bioexcel.eu/t/urgent-help-error-atoms-are-not-part-of-any-of-the-t-coupling-groups/6844/3 "2023-07-16T07:15:39Z")
thank you @Karis for reply. i used this command but the issue was not resolved. I did it another way: actually my protein had Hem group in it and when i check it has 73 atoms. according to my docking studies Lig should show interaction with protein and Hem as well. so while generating index file i combined protein, Hem and lig togatehr and in nvt.mdp file i changed the tc grp from **Protein\_Lig water and ions to Protein\_Hem\_Lig Water\_and\_ions**. and it worked for me. Is that a good way to do this ? ---
**Author:** ![Karis](https://avatars.discourse-cdn.com/v4/letter/k/ed8c4c/32.png) [@Karis](https://gromacs.bioexcel.eu/u/Karis)\ **Post date:** [July 16, 2023, 11:03am UTC](https://gromacs.bioexcel.eu/t/urgent-help-error-atoms-are-not-part-of-any-of-the-t-coupling-groups/6844/4 "2023-07-16T11:03:55Z")
That should be fine ---
**Author:** ![shanza](https://avatars.discourse-cdn.com/v4/letter/s/4491bb/32.png) [@shanza](https://gromacs.bioexcel.eu/u/shanza)\ **Post date:** [July 16, 2023, 11:09am UTC](https://gromacs.bioexcel.eu/t/urgent-help-error-atoms-are-not-part-of-any-of-the-t-coupling-groups/6844/5 "2023-07-16T11:09:41Z")
Alright thank you :)