The different bond parameters obtained from LigParGen and from oplsaa.ff in Gromacs

GROMACS version:2020.3
GROMACS modification: No
Here post your question:I have a small and foolish question. The values I obtained from LigParGen are different to what I get it from oplsaa.ff OPLS-AA force field distributed with GROMACS. Taking ethanol for example, the CT-CT bond obtain from LigParGen is “268.00 1.5290” and the values from the oplsaa.ff is “0.153 2.24e+05”, corresponds to “CT CT 1 0.15290 224262.4; CHARMM 22 parameter file”. I do not know why they are different and how can I correctly use the values obtained from oplsaa.ff. Because many atoms can be identified by TPPMKTOP but not by LigParGen. Can anyone give me some suggestions?
I would be very grateful indeed for any help you could give me.
Best wishes.

The values are the same, just in different units. The force constant from LigParGen is in kcal mol-1 Å-2 (and appears to likely be already expressed as k/2 instead of k, and GROMACS format is kJ mol-1 nm-2, so 268 * 2 * 100 * 4.184 = 224262.4. The reference bond length is simply in Å instead of nm.