# How to create a contact map between an especific aminoacids group?

**URL:** <https://gromacs.bioexcel.eu/t/how-to-create-a-contact-map-between-an-especific-aminoacids-group/1113>\
**Category:** User discussions\
**Created:** [November 18, 2020, 3:02pm UTC](https://gromacs.bioexcel.eu/t/how-to-create-a-contact-map-between-an-especific-aminoacids-group/1113 "2020-11-18T15:02:00Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mario](https://avatars.discourse-cdn.com/v4/letter/m/8e7dd6/32.png) [@mario](https://gromacs.bioexcel.eu/u/mario)\
**Post date:** [November 18, 2020, 3:02pm UTC](https://gromacs.bioexcel.eu/t/how-to-create-a-contact-map-between-an-especific-aminoacids-group/1113/1 "2020-11-18T15:02:01Z")

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GROMACS version: 2020.4  
GROMACS modification: No  
Here post your question

Hi everyone i have a gromacs trajectory and i want to create a contact map for some specific aminoacid in a region of my protein. Anyone can tell me how i can do this?  
Thanks a lot.

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**Author:** ![cblau](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/cblau/32/5_2.png) [@cblau](https://gromacs.bioexcel.eu/u/cblau)\
**Post date:** [November 18, 2020, 3:22pm UTC](https://gromacs.bioexcel.eu/t/how-to-create-a-contact-map-between-an-especific-aminoacids-group/1113/2 "2020-11-18T15:22:33Z")

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Hi Mario,

you can have a go with `gmx mindist` which tells you if things were in contact or not.

If you’re not afraid of compiling some old code, you can have a try with [g\_contacts](http://cpc.cs.qub.ac.uk/summaries/AEQA_v1_0.html) which has an option to give you per-residue contact frequencies (read more [here](https://www.sciencedirect.com/science/article/pii/S0010465513002464) ;) )

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**Author:** ![mario](https://avatars.discourse-cdn.com/v4/letter/m/8e7dd6/32.png) [@mario](https://gromacs.bioexcel.eu/u/mario)\
**Post date:** [December 2, 2020, 5:24pm UTC](https://gromacs.bioexcel.eu/t/how-to-create-a-contact-map-between-an-especific-aminoacids-group/1113/3 "2020-12-02T17:24:41Z")

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I have gromacs 2019.4  
I’m trying to use mindist but i don’t understand how to insert the data to do this analysis. Can you tell me if i need to insert an index?  
The index is for an especific atom or can be an aminoacid residue?  
Thanks for your help.