Dear LAMMPS users,

I want to calculate the number of hydrogen bonds in my system. As I understand, there is no direct way to do this via any computes (is it correct?). From an old discussion Hydrogen bonding distance and angle cutoff I conclude that I can try to use hbond/dreiding/lj pair_style to define the Hbonds in the system (by defining the A-H-D cutoff angle and A-D cutoff distance) during postprocessing. As I understand, I can use

```
pair_style hybrid/overlay [potential that I used during the simulation] hbond/dreiding/lj 4 2 3.5 120 (assuming 3.5 and 120 are the distance and the angle in the Hbond definition)
```

and get the number of hydrogen bonds in the system by

```
compute hb all pair hbond/dreiding/lj
variable n_hbond equal c_hb[1] #number hbonds
thermo_style custom step temp v_n_hbond
```

Is it okay to use this pair_style with other potentials, say lj/cut/tip4p/long, with hybrid/overlay assuming that I do not run any kind of simulation but just do this Hbond counting for a single frame as postprocessing? Does it only compute the number of interactions that satisfy the distance/angle criteria?

Thank you in advance.