# Force parameter in topology \[angles\] option **URL:** \ **Category:** User discussions\ **Created:** [June 15, 2021, 9:59pm UTC](https://gromacs.bioexcel.eu/t/force-parameter-in-topology-angles-option/2366 "2021-06-15T21:59:27Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Lois](https://avatars.discourse-cdn.com/v4/letter/l/5f8ce5/32.png) [@Lois](https://gromacs.bioexcel.eu/u/Lois)\ **Post date:** [June 15, 2021, 9:59pm UTC](https://gromacs.bioexcel.eu/t/force-parameter-in-topology-angles-option/2366/1 "2021-06-15T21:59:28Z")
GROMACS version: 2016.4 GROMACS modification: Yes/No Dear all, Recently I have come across a .top file with the following: [angles] ; i j k func angle force 1 2 3 1 180 100 I am aware of what all of these parameters mean apart from ‘force’ which I cannot find in any GROMACS documentation, although perhaps I’m looking in the wrong places. Apologies, I am very new to GROMACS, but does anyone know what it means? Thanks in advance. ---
**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\ **Post date:** [June 15, 2021, 10:11pm UTC](https://gromacs.bioexcel.eu/t/force-parameter-in-topology-angles-option/2366/2 "2021-06-15T22:11:26Z")
It’s the force constant in the harmonic potential. See [File formats — GROMACS 2021.2 documentation](https://manual.gromacs.org/current/reference-manual/topologies/topology-file-formats.html#tab-topfile2) ---
**Author:** ![Lois](https://avatars.discourse-cdn.com/v4/letter/l/5f8ce5/32.png) [@Lois](https://gromacs.bioexcel.eu/u/Lois)\ **Post date:** [June 15, 2021, 10:18pm UTC](https://gromacs.bioexcel.eu/t/force-parameter-in-topology-angles-option/2366/3 "2021-06-15T22:18:01Z")
Ah I see, thank you so much!