# No default Improper Dih. types

**URL:** <https://gromacs.bioexcel.eu/t/no-default-improper-dih-types/10398>\
**Category:** User discussions\
**Tags:** forcefield, simulation-setup\
**Created:** [October 22, 2024, 5:29pm UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types/10398 "2024-10-22T17:29:08Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![MagnusL](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/magnusl/32/2380_2.png) [@MagnusL](https://gromacs.bioexcel.eu/u/MagnusL)\
**Post date:** [October 23, 2024, 4:17am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types/10398/2 "2024-10-23T04:17:29Z")

</div>

All `[<bond,angle,dihedral,...>types]` sections must come before the first `[molecule types]` section, see [Common errors when using GROMACS - GROMACS 2024.3 documentation](https://manual.gromacs.org/current/user-guide/run-time-errors.html#invalid-order-for-directive-xxx).

The other errors you are getting before is because of the same error, i.e., the parameters of bonded interactions are not defined when you use them. Move bonded and non-bonded `[...types]` sections to a separate file and include that after the `forcefield.itp` in your topology file.

---

_[View the full topic](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types/10398)._