For molecular modelers, minimizing structures to achieve optimized geometries is a routine task. However, selectively minimizing only specific parts of a molecular system can sometimes be challenging, especially when working with large or complex structures. Thankfully, SAMSON provides features tailored for such needs. In this guide, we’ll focus on how to minimize a single molecule or a specific part of a molecule within a larger molecular document. This approach is particularly helpful when you want precise control over what gets optimized.
Why Minimize Selectively?
Imagine working on a multi-molecule system, but you only need to refine one molecule’s geometry without disturbing the others. Or perhaps you’re focusing on functional groups or specific regions within a larger molecule. Minimizing the entire structure in such cases might introduce unwanted changes to components you wish to leave untouched. With SAMSON, you can zero in on particular molecules or even parts of molecules, streamlining your molecular design process.
Minimizing a Single Molecule
To minimize a single molecule in your document while keeping the rest unchanged, follow these steps:
- Open the Preferences panel (Interface > Preferences > Editors > Minimize) and uncheck the option to Include all atoms in the document.
- Select the molecule you wish to minimize. If you’re unsure about selection tools in SAMSON, you can refer to the Selecting section of the documentation for guidance.
- Click Edit > Minimize (shortcut: Z) to start the optimization process.
During this process, SAMSON focuses on minimizing the selected molecule while the rest of the system remains unaffected. This is particularly useful for projects requiring higher precision and targeted optimizations.
Note
When minimizing with a selection, SAMSON automatically considers the entire connected component of your selection. For instance, selecting a single atom in a molecule will result in the minimization of the entire molecule to which the atom belongs.
Minimizing a Part of a Molecule
What if you only want to minimize a specific region of a molecule? This scenario arises when targeting localized optimizations like tweaking active sites in proteins or specific bonds. Here’s how you can achieve that in SAMSON:
- Select the entire molecule, or leave the selection empty.
- Freeze the whole molecule by clicking Edit > Freeze. This step ensures the molecule’s current state remains intact.
- Select the specific part of the molecule you want to optimize.
- Unfreeze this selection by clicking Edit > Unfreeze. Only the selected atoms will now be eligible for minimization.
- Click Edit > Minimize to initiate the optimization for the active selection.
Once you’ve completed the process, you can unfreeze the entire molecule or leave it as is. A useful visual cue in SAMSON is that frozen atoms are displayed with a dark blue overlay, making it easy to distinguish between frozen and active regions.
Need More Insights?
If you’re working on advanced simulations or need to understand optimization approaches better, consider exploring the simulators section, which provides more details about force fields and state updaters.
For additional tips and examples, check out the original documentation page at SAMSON Minimizing Documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at www.samson-connect.net.