Problem during hbond calculation per water molecule using gmx hbond

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1

GROMACS version:
GROMACS modification: Yes/No
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I am calculating h bond of SPC/E water using gmx hbond tool. I got approximate 1.8 hydrogen bond per water molecule. But one water molecule can form 4 hbond. I think they calculate hbond between O atom of one water to the H atom of others. But they didn’t consider the two H atoms of one water to the O atom of other water molecule. How can we solve it. Please help.

2

The default behavior is to merge equivalent hydrogens (consider them equivalent), so if you want to disable this, use -nomerge.

3

I am facing the same issue.
I tried calculating the average number of Hydrogen bonds (HBs) per SPC water molecule with gmx hbond with -nomerge. However, I still get around 1.8 HBs per water molecule. What could be the problem?

GROMACS version: 2022.4