# Tc-grps value

**URL:** <https://gromacs.bioexcel.eu/t/tc-grps-value/5071>\
**Category:** User discussions\
**Tags:** mdrun\
**Created:** [October 21, 2022, 3:11am UTC](https://gromacs.bioexcel.eu/t/tc-grps-value/5071 "2022-10-21T03:11:04Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![shivam1](https://avatars.discourse-cdn.com/v4/letter/s/b3f665/32.png) [@shivam1](https://gromacs.bioexcel.eu/u/shivam1)\
**Post date:** [October 21, 2022, 3:11am UTC](https://gromacs.bioexcel.eu/t/tc-grps-value/5071/1 "2022-10-21T03:11:05Z")

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GROMACS version:2022.2  
GROMACS modification: No  
I want to run MD simulation to predict Antigen-Antibody interaction (Protein-protein) in a PBS buffer of pH-7.4 and at 303 K temp. What modifications do I need to make in a standard mdp file. Here are the changes, I can come up with. Please let me know if I am mistaken.

```auto
**Parameter** = **Standard Value** -> **Modified Value**

tc-grps = Protein Non-Protein -> Protein Protein
ref_t = 298 298 -> 303 303
gen_temp = 298 -> 303                     
annealing_temp = 50 298 50 298 -> 50 303 50 303

```

Since I am new to MD/Gromacs, Please guide me if these modification are good enough to perform MD simulation for aforementioned conditions or Do I need to add more conditions?

Thanks

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**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:** [October 21, 2022, 3:32am UTC](https://gromacs.bioexcel.eu/t/tc-grps-value/5071/2 "2022-10-21T03:32:56Z")

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Use the “standard” settings with the temperature changed to 303. The `annealing_temp` does nothing here in the absence of other settings controlling this behavior. Defining `Protein` twice with both (1) trigger an error about overlapping groups and (2) is nonsensical because you haven’t coupled your solvent to any thermostat. Distinct protein chains do not necessitate their own groups. Stick with `Protein Non-Protein` for `tc-grps`.

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<div class="post-metadata">

**Author:** ![shivam1](https://avatars.discourse-cdn.com/v4/letter/s/b3f665/32.png) [@shivam1](https://gromacs.bioexcel.eu/u/shivam1)\
**Post date:** [October 21, 2022, 4:39am UTC](https://gromacs.bioexcel.eu/t/tc-grps-value/5071/3 "2022-10-21T04:39:33Z")

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Thank you so much. It helped me alot.