# Energygrp-excl

**URL:** <https://gromacs.bioexcel.eu/t/energygrp-excl/434>\
**Category:** User discussions\
**Created:** [July 6, 2020, 5:15pm UTC](https://gromacs.bioexcel.eu/t/energygrp-excl/434 "2020-07-06T17:15:21Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Julius](https://avatars.discourse-cdn.com/v4/letter/j/ecd19e/32.png) [@Julius](https://gromacs.bioexcel.eu/u/Julius)\
**Post date:** [July 6, 2020, 5:15pm UTC](https://gromacs.bioexcel.eu/t/energygrp-excl/434/1 "2020-07-06T17:15:21Z")

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I want to determine if the interactions between two energy groups have an effect on a specific phenomenon I observe in my simulations. I was wondering if using “Energygrp-excl” only excludes the calculations of the energies or it also completely excludes the interactions such that the system behaves as though the interactions of the said molecules do not exist.

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**Author:** ![Masrul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/masrul/32/234_2.png) [@Masrul](https://gromacs.bioexcel.eu/u/Masrul)\
**Post date:** [July 6, 2020, 7:12pm UTC](https://gromacs.bioexcel.eu/t/energygrp-excl/434/2 "2020-07-06T19:12:23Z")

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For your purpose, _ **energygrps** _ option is sufficient. _ **Energygrp-Excl** _ is useful for the frozen system to avoid spurious pressure.

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**Author:** ![Julius](https://avatars.discourse-cdn.com/v4/letter/j/ecd19e/32.png) [@Julius](https://gromacs.bioexcel.eu/u/Julius)\
**Post date:** [July 8, 2020, 3:55pm UTC](https://gromacs.bioexcel.eu/t/energygrp-excl/434/3 "2020-07-08T15:55:08Z")

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Thanks

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**Author:** ![Julius](https://avatars.discourse-cdn.com/v4/letter/j/ecd19e/32.png) [@Julius](https://gromacs.bioexcel.eu/u/Julius)\
**Post date:** [July 15, 2020, 2:59pm UTC](https://gromacs.bioexcel.eu/t/energygrp-excl/434/4 "2020-07-15T14:59:13Z")

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I know that Energygrp-Excl does not work well with Verlet so i used group but then i still get a warning that “Can not exclude the lattice coulomb energy between energy groups” does this affect the purpose of using energygrp-excl as stated earlier? Also does energygrp-excl work well with gpu? Thanks

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**Author:** ![Masrul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/masrul/32/234_2.png) [@Masrul](https://gromacs.bioexcel.eu/u/Masrul)\
**Post date:** [July 15, 2020, 5:40pm UTC](https://gromacs.bioexcel.eu/t/energygrp-excl/434/5 "2020-07-15T17:40:21Z")

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Warning is a fundamental problem! You are simply seeing this warning due to the way PME summation works. Point charges are interpolated into 3D grid in PME, and interpolated charges are indistinguishable for exclusion purpose.