# Manual Error Regarding Rhombic Dodecahedral Cell?

**URL:** https://gromacs.bioexcel.eu/t/manual-error-regarding-rhombic-dodecahedral-cell/9024
**Category:** User discussions
**Tags:** pbc
**Created:** [April 29, 2024, 7:27pm UTC](https://gromacs.bioexcel.eu/t/manual-error-regarding-rhombic-dodecahedral-cell/9024 "2024-04-29T19:27:14Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Starsy](https://avatars.discourse-cdn.com/v4/letter/s/eb8c5e/32.png) [@Starsy](https://gromacs.bioexcel.eu/u/Starsy)
#### Post date: [April 29, 2024, 7:27pm UTC](https://gromacs.bioexcel.eu/t/manual-error-regarding-rhombic-dodecahedral-cell/9024/1 "2024-04-29T19:27:14Z")

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Dear GROMACS Users (and Developers),

I think I may have spotted a small error on [this page](https://manual.gromacs.org/current/reference-manual/algorithms/periodic-boundary-conditions.html) of the manual, in table 6.

For the xy-square version of the Rhombic Dodecahedron, all the box vector angles are given as 60 degrees. However, the angle \<ab should be 90 degrees since a and b are clearly orthogonal, right? I think this is a mistake but want to double check I’m not missing something.

Additionally, for the Truncated Octahedron, the angles \<ab and \<bc are given as 71.53 degrees, but I believe these should be 70.53 degrees. The latter leads to the correct volume of 0.770d^3 using:  
 ![image](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/7/73b8c2c9426292065c7e632fb8e56fba81615c21.png)

Peter

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### Author: ![hess](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/hess/32/416_2.png) [@hess](https://gromacs.bioexcel.eu/u/hess)
#### Post date: [April 30, 2024, 12:18pm UTC](https://gromacs.bioexcel.eu/t/manual-error-regarding-rhombic-dodecahedral-cell/9024/2 "2024-04-30T12:18:30Z")

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Strange that no one noticed this before (and that I made these mistakes in the first place).

I uploaded a fix for 2024.

Thanks for reporting this.