# Strange numbers on hbnum.xvg - Hbond Analysis

**URL:** <https://gromacs.bioexcel.eu/t/strange-numbers-on-hbnum-xvg-hbond-analysis/11827>\
**Category:** User discussions\
**Tags:** gmx-hbond\
**Created:** [March 28, 2025, 1:41am UTC](https://gromacs.bioexcel.eu/t/strange-numbers-on-hbnum-xvg-hbond-analysis/11827 "2025-03-28T01:41:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Daphney](https://avatars.discourse-cdn.com/v4/letter/d/13edae/32.png) [@Daphney](https://gromacs.bioexcel.eu/u/Daphney)\
**Post date:** [March 28, 2025, 1:41am UTC](https://gromacs.bioexcel.eu/t/strange-numbers-on-hbnum-xvg-hbond-analysis/11827/1 "2025-03-28T01:41:53Z")

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GROMACS version:  
GROMACS modification: Yes/No  
Here post your question  
I used this command gmx hbond -f md\_0\_1.xtc -s md\_0\_1.tpr -n index.ndx -num hbnum.xvg for my analysis after creating an index file. However, I am getting strange numbers (Screenshot attached) when I open the hbnum.xvg and when I try to visualize the file on xmgrace, the graph is blank. My simulations were 1µs long.

Please assist  
Thank you.

 ![Screenshot (1)](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/4/401c1409f2237e8fa0a04f8167707fe87d0f455b.png)

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**Author:** ![alevilla](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/alevilla/32/439_2.png) [@alevilla](https://gromacs.bioexcel.eu/u/alevilla)\
**Post date:** [March 28, 2025, 2:18pm UTC](https://gromacs.bioexcel.eu/t/strange-numbers-on-hbnum-xvg-hbond-analysis/11827/2 "2025-03-28T14:18:43Z")

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Hi,  
It might be useful to know which version of GROMACS you are using.  
see

> [@Gromacs hbond problem - 1 frame with high number of hbonds](https://gromacs.bioexcel.eu/t/gromacs-hbond-problem-1-frame-with-high-number-of-hbonds/7002):
>
> GROMACS version: 2023 GROMACS modification: Yes - with plumed Hi, I am trying to analyze hbonds between a molecule and a protein. The complex was generated using CHARM-GUI so there is .itp file for the molecule. I am using gromacs gmx hbond command with 2 groups I have created (the molecule with 45 atoms and the protein with around 7500 atoms). This is the exact command: “gmx\_mpi hbond -f step5\_1.xtc -s step5\_1.tpr -n updated\_index.ndx -num hb1.xvg” The times are in picoseconds, each frame…

\Alessandra