# No default Improper Dih. types Error in AMBER **URL:** \ **Category:** User discussions\ **Created:** [August 4, 2020, 12:04am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619 "2020-08-04T00:04:02Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![L\_k](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@L\_k](https://gromacs.bioexcel.eu/u/L_k)\ **Post date:** [August 4, 2020, 12:04am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/1 "2020-08-04T00:04:02Z")
GROMACS version: 2020.2 I have encountered the following error when trying to write a tpr file using the ff14sb AMBER force field: ERROR 6 [file topol\_Protein\_chain\_B.itp, line 142001]: No default Improper Dih. types. I have seen that ffbonded.itp may have to be edited. Are there any other approaches/any explanations for why I may be receiving this error? ---
**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:** [August 4, 2020, 12:13am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/2 "2020-08-04T00:13:22Z")
Where did you get ff14SB force field files? Whoever produced them may not have done a very thorough job of validating them, so be skeptical of their quality. Missing a parameter in a protein is a pretty massive oversight. ---
**Author:** ![L\_k](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@L\_k](https://gromacs.bioexcel.eu/u/L_k)\ **Post date:** [August 4, 2020, 12:15am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/3 "2020-08-04T00:15:05Z")
Okay, I see. The files are from: [https://fch.upol.cz/ff\_ol/gromacs.php](https://fch.upol.cz/ff_ol/gromacs.php) . Is there somewhere else that they should be sourced from? ---
**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:** [August 4, 2020, 12:27am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/4 "2020-08-04T00:27:43Z")
No idea, but it looks like they took a user contribution off of [gromacs.org](http://gromacs.org) and there’s no guarantee that those files are correct. They appear to have done validation, but the question really is: what is the missing parameter? Some corner case they might have missed, something weird like a Gly-Pro linkage that got overlooked? ---
**Author:** ![L\_k](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@L\_k](https://gromacs.bioexcel.eu/u/L_k)\ **Post date:** [August 4, 2020, 1:03am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/5 "2020-08-04T01:03:47Z")
I have come across the following, but I am a bit unsure of this approach. Further thoughts?: [http://zhenglz.blogspot.com/2017/05/fixing-bugs-in-ff14sb-port-for-gromacs.html](http://zhenglz.blogspot.com/2017/05/fixing-bugs-in-ff14sb-port-for-gromacs.html) ---
**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:** [August 4, 2020, 1:15am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/6 "2020-08-04T01:15:17Z")
Compare the values against the original AMBER force field files and if they match (after unit conversion), then that’s an appropriate fix. Really anyone distributing a force field port should also be doing validation to avoid such problems. ---
**Author:** ![L\_k](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@L\_k](https://gromacs.bioexcel.eu/u/L_k)\ **Post date:** [August 4, 2020, 8:25pm UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/7 "2020-08-04T20:25:11Z")
Do you happen to have a source for the ff14sb files? I cannot seem to download them. If so, that would be great. Also, I am unsure where there would need to be a conversion exactly. Thank you for all of your help. ---
**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:** [August 5, 2020, 3:58pm UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/8 "2020-08-05T15:58:11Z")
You can get the force field files with the (free) AmberTools package. ---
**Author:** ![L\_k](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@L\_k](https://gromacs.bioexcel.eu/u/L_k)\ **Post date:** [August 10, 2020, 7:59pm UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/9 "2020-08-10T19:59:22Z")
Got them, thank you for all of your help. ---
**Author:** ![wichadak](https://avatars.discourse-cdn.com/v4/letter/w/a4c791/32.png) [@wichadak](https://gromacs.bioexcel.eu/u/wichadak)\ **Post date:** [January 1, 2021, 10:42am UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/10 "2021-01-01T10:42:12Z")
I followed the [Fixing bugs in FF14SB port for Gromacs](http://zhenglz.blogspot.com/2017/05/fixing-bugs-in-ff14sb-port-for-gromacs.html) and can fix the “No default Improper Dih. types” error. I downloaded the amber14sb\_parmbsc1.ff.tar.gz from [Force fields - Gromacs](http://www.gromacs.org/Downloads/User_contributions/Force_fields) and needed to edit by adding on more line NA CV CC CT 4 180.00 4.60240 2 at line 783 to the amber14sb\_parmbsc1.ff/ffbonded.itp. Then, it works! ---
**Author:** ![L\_k](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@L\_k](https://gromacs.bioexcel.eu/u/L_k)\ **Post date:** [January 1, 2021, 7:35pm UTC](https://gromacs.bioexcel.eu/t/no-default-improper-dih-types-error-in-amber/619/11 "2021-01-01T19:35:05Z")
This worked perfectly, thank you!