# Invalid T coupling input

**URL:** <https://gromacs.bioexcel.eu/t/invalid-t-coupling-input/10657>\
**Category:** User discussions\
**Created:** [November 28, 2024, 11:16am UTC](https://gromacs.bioexcel.eu/t/invalid-t-coupling-input/10657 "2024-11-28T11:16:36Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![m.m](https://avatars.discourse-cdn.com/v4/letter/m/958977/32.png) [@m.m](https://gromacs.bioexcel.eu/u/m.m)\
**Post date:** [November 28, 2024, 11:16am UTC](https://gromacs.bioexcel.eu/t/invalid-t-coupling-input/10657/1 "2024-11-28T11:16:36Z")

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Hi  
Can you please help me fix the following error I encountered during the nvt step?  
invalid T coupling input: 1 groups, 2 ref-t values and 2 tau-t values.

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**Author:** ![MagnusL](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/magnusl/32/2380_2.png) [@MagnusL](https://gromacs.bioexcel.eu/u/MagnusL)\
**Post date:** [November 28, 2024, 12:00pm UTC](https://gromacs.bioexcel.eu/t/invalid-t-coupling-input/10657/2 "2024-11-28T12:00:00Z")

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I’m not sure I understand what is unclear. You can’t have 2 temperature values and thermostat settings for one temperature coupling group. Have a look at [Molecular dynamics parameters (.mdp options) - GROMACS 2024.4 documentation](https://manual.gromacs.org/current/user-guide/mdp-options.html#temperature-coupling).

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<div class="post-metadata">

**Author:** ![m.m](https://avatars.discourse-cdn.com/v4/letter/m/958977/32.png) [@m.m](https://gromacs.bioexcel.eu/u/m.m)\
**Post date:** [November 29, 2024, 8:27am UTC](https://gromacs.bioexcel.eu/t/invalid-t-coupling-input/10657/3 "2024-11-29T08:27:09Z")

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Thank you for your guidance.