# Expand box size for simulation

**URL:** <https://gromacs.bioexcel.eu/t/expand-box-size-for-simulation/10110>\
**Category:** User discussions\
**Created:** [September 6, 2024, 1:37am UTC](https://gromacs.bioexcel.eu/t/expand-box-size-for-simulation/10110 "2024-09-06T01:37:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![nhina](https://avatars.discourse-cdn.com/v4/letter/n/46a35a/32.png) [@nhina](https://gromacs.bioexcel.eu/u/nhina)\
**Post date:** [September 6, 2024, 1:37am UTC](https://gromacs.bioexcel.eu/t/expand-box-size-for-simulation/10110/1 "2024-09-06T01:37:26Z")

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GROMACS version: 2019  
GROMACS modification: Yes/No  
Here post your question  
Hi guys,

I have a simulation of protein-ligand system in dodecahedron box created by command gmx editconf -bt dodecahedron -c -d 1.2 -f rec.pdb -o rec.pdb. I want to expand box size to 300nm^3 for all system so how can I do that? It would be great if you can give me some refferences or guidelines to resolve this problem.

Thank you so much.

Nhina

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**Author:** ![milosz.wieczor](https://avatars.discourse-cdn.com/v4/letter/m/b19c9b/32.png) [@milosz.wieczor](https://gromacs.bioexcel.eu/u/milosz.wieczor)\
**Post date:** [September 6, 2024, 11:17am UTC](https://gromacs.bioexcel.eu/t/expand-box-size-for-simulation/10110/2 "2024-09-06T11:17:51Z")

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During processing, `editconf` gives you the box dimensions and volume. If you want to have exactly 300 nm³ with the same box geometry, take your ratio of the desired and current volume, calculate the cubic square, and use the `-scale sc_x sc_y sc_z` option, placing the cubic square as the respective scaling factors. Then `editconf` should give you the desired box volume.

In case you already have solvent/ions/… in your system, discarding them and resolving from scratch might be easier, depending on where you are in the workflow.

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**Author:** ![nhina](https://avatars.discourse-cdn.com/v4/letter/n/46a35a/32.png) [@nhina](https://gromacs.bioexcel.eu/u/nhina)\
**Post date:** [September 10, 2024, 1:31am UTC](https://gromacs.bioexcel.eu/t/expand-box-size-for-simulation/10110/3 "2024-09-10T01:31:13Z")

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thank you so much