Getting consistent results across machines and ensuring reproducibility in molecular simulations is a real challenge. While default software versions bundled with simulation tools are great for convenience, you might have faced cases where:
- You need to match the exact GROMACS version used in a previous study.
- You’ve optimized a custom GROMACS build for specific hardware.
- You simply want to stay on the same version across different environments.
If you’re using SAMSON’s GROMACS Wizard, there’s a handy way to switch to your own GROMACS version for local computations. Let’s walk through how you can do this, and why it’s useful.
Why use a custom GROMACS version?
The version of GROMACS you use can impact your simulation results due to changes in algorithms, bug fixes, or performance-related optimizations. While SAMSON comes with a recent GROMACS version, working with your own version might be essential when:
- Reproducing results from published work.
- Aligning your workflow with a specific computational infrastructure.
- Using extensions or compiled modifications specific to your GROMACS build.
How to switch to a custom GROMACS version in SAMSON
First, open the Settings in the GROMACS Wizard:

Check the option Use a different GROMACS version and you’ll be able to provide two key pieces of information:
- Path to GROMACS executable:
You’ll need to locate your compiled GROMACS executable on your system. This is generally calledgmx(Linux/Mac) orgmx.exe(Windows). Click the browse button
to select it. Once selected, SAMSON will try to validate the executable and display its version (or show “invalid” if it can’t recognize it). - Path to force fields:
You also need to specify the path to the folder containing your GROMACS force fields, typically something like$HOME/gromacs/share/top/.

Things to keep in mind
- You can always switch back to the default bundled GROMACS version, which is useful if you’re collaborating with colleagues who don’t use a custom version.
- Make sure that your local GROMACS version is compiled with the options you expect (e.g., GPU support, MPI) before using it in your simulations.
- This setup only affects local jobs. Cloud jobs will still use the default settings from SAMSON’s infrastructure.
Conclusion
Being able to use a custom GROMACS version within SAMSON gives you more control and flexibility, helping address key pain points like reproducibility and tailored performance optimizations. If you’ve already installed a specialized GROMACS build on your machine, making SAMSON’s GROMACS Wizard use it is just a few clicks away.
📘 Learn more in the full GROMACS Wizard settings documentation.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can get SAMSON at https://www.samson-connect.net.
