For molecular modelers, precision is essential. However, minimizing entire molecules or systems when you are interested in only a specific region can be inefficient and inaccurate for your modeling goals. SAMSON offers a tailored solution to this pain: selectively minimizing parts of a molecule while freezing the rest.
Why Minimize Only Part of a Molecule?
When working on molecular systems, you might need to refine the geometry or optimize the region of interest (e.g., a bond, a chain, or a specific functional group) without affecting the rest of the molecule. For instance, in large systems, blindly minimizing everything might introduce unnecessary alterations to parts that are already in optimal positions. This can waste computation time and introduce unwanted changes into your model.
In SAMSON, the interactive minimization workflow allows precise control: you can freeze parts of the molecule that you want to remain fixed while applying minimization to the selected region of interest.
How It Works
The process of minimizing a part of a molecule involves a few straightforward steps:
- Select the entire molecule, or leave the selection empty to target the whole structure.
- Freeze the areas you want to remain fixed by clicking
Edit > Freeze. This locks the selected atoms in place, ensuring that they will not change during minimization. - Specify the part of the molecule that you’d like to minimize by making a precise selection.
- Unfreeze the selected region by clicking
Edit > Unfreeze. This ensures only these atoms are flexible and can undergo minimization. - Run the minimization interactively by selecting
Edit > Minimize. You will see how the targeted region adjusts based on the force field used, while the frozen areas remain fixed.
Once done, you can unfreeze the entire system to restore its full flexibility if needed. Frozen atoms are visually marked with a dark blue overlay in SAMSON’s viewport, making it easy to distinguish between fixed and active areas as you work.
Why Use SAMSON for Selective Minimization?
Selective minimization in SAMSON is particularly valuable for large systems where certain regions—such as bound ligands or particular protein residues—require adjustment while the rest remains untouched. The interactive approach makes it intuitive to experiment with molecule manipulation, and the visual cues (like atom overlays) keep you informed throughout the process.
The frozen atoms, during simulation, are excluded from computational adjustments, saving time and computational resources. This approach is ideal for tasks such as optimizing specific binding sites, evaluating geometric adjustments on active regions, or ensuring that one part of your system remains stable during iterative modeling workflows.
Learn More About Minimization
Want to understand the full details of how SAMSON handles molecule minimization, including freezing techniques and advanced settings? Visit the original documentation page at https://documentation.samson-connect.net/users/latest/minimizing/.
And don’t forget, frozen atoms are not just visually distinct—they ensure that your optimization is focused and efficient. Check out the useful video below illustrating a minimization example with frozen atoms in action:
Precision and efficiency combined. Give it a try and take control of your molecular modeling workflows!
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at https://www.samson-connect.net.