# Should I swap group order and sum results for hydrogen bond counts when using \`gmx hbond\`?

**URL:** <https://gromacs.bioexcel.eu/t/should-i-swap-group-order-and-sum-results-for-hydrogen-bond-counts-when-using-gmx-hbond/12733>\
**Category:** User discussions\
**Tags:** gmx-hbond\
**Created:** [October 5, 2025, 3:08am UTC](https://gromacs.bioexcel.eu/t/should-i-swap-group-order-and-sum-results-for-hydrogen-bond-counts-when-using-gmx-hbond/12733 "2025-10-05T03:08:45Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![liuwq](https://avatars.discourse-cdn.com/v4/letter/l/c37758/32.png) [@liuwq](https://gromacs.bioexcel.eu/u/liuwq)\
**Post date:** [October 5, 2025, 3:08am UTC](https://gromacs.bioexcel.eu/t/should-i-swap-group-order-and-sum-results-for-hydrogen-bond-counts-when-using-gmx-hbond/12733/1 "2025-10-05T03:08:45Z")

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Hello everyone,

Could you please guide me on whether it’s necessary to run `gmx hbond` twice? That said, for two different groups without overlapping, first input `Group1` and then input `Group2` in the prompt window. And then swapping the order (first `Group2` and then `Group1`), and finally summing the results as the hydrogen-bond count between the two groups? I read the manual, but it seems this particular aspect is not clearly mentioned. Any help would be greatly appreciated.