As a molecular modeler, you often encounter situations where you only need to refine or optimize specific regions of a molecule without disturbing the rest of the structure. This could be when fine-tuning a specific functional group, testing modifications, or minimizing a local geometry that impacts the molecule’s function. The good news? SAMSON offers an efficient way to achieve this using its partial minimization feature.
Partial minimization in SAMSON is an incredibly versatile tool that allows you to freeze parts of a molecule, preventing them from being altered during minimization. This maintains their positions while focusing the optimization strictly on the selected regions. Here’s a step-by-step guide to making the most of this feature:
Step 1: Selection Setup
Before you begin, decide whether you want to work on the entire molecule or a specific region:
- Use the Selecting feature to highlight the molecule or region you’d like to optimize. Or, you can leave the selection empty if you want to prepare the whole molecule for specific customizations.
Step 2: Freezing the Unwanted Parts
Freezing atoms is essential to prevent specific portions of the molecule from being altered:
- Click Edit > Freeze. This will freeze all selected atoms or the entire molecule if no active selection is made.
The frozen atoms will appear with a dark blue overlay in the viewport, easily distinguishing them from the active regions.
Step 3: Select the Active Region
Now, select the part of the molecule you’d like to minimize. You can do this using the same Selecting tool as earlier, but now focus only on the specific region you wish to refine.
Step 4: Unfreezing the Active Region
To activate only the selected part for minimization:
- Click Edit > Unfreeze.
This ensures that only the selected atoms will participate in the optimization while the frozen parts remain untouched.
Step 5: Minimizing
Now, it’s time for the actual minimization:
- Click Edit > Minimize to begin interactively refining the selected region.
Once satisfied, click Edit > Minimize again to stop the process.
Step 6: Unfreezing the Entire System
Once the partial minimization is complete, bring the entire molecule back to its active state by unfreezing all atoms:
- Click Edit > Unfreeze with the molecule selected, or click it without making a selection to unfreeze the entire document.
Visual Feedback
This freeze-and-unfreeze workflow gives you fine control, preventing unwanted changes to critical regions. The visualization of frozen atoms as dark blue overlays ensures clarity during the process.
Here’s an example from the SAMSON interface:
For more details, you can view the associated video example in the full documentation, demonstrating how to optimize molecular structures while keeping certain regions fixed.
Partial minimization not only gives you precise control over structural edits but also helps streamline workflows when dealing with large or complex models.
For a comprehensive understanding of this and related topics, visit the original documentation page: https://documentation.samson-connect.net/users/latest/minimizing/.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Experience the power of molecular modeling by downloading SAMSON today at https://www.samson-connect.net.