When working with molecular models, precision matters. Whether you’re aligning atoms for structural comparison, assembling molecules symmetrically around a core, or preparing a visualization for publication, even slight errors in position and orientation can impact your results significantly.
One common challenge for molecular modelers is how to position molecular fragments precisely along specific distances and angles. Doing this manually often involves guesswork, especially when moving multiple fragments into symmetrical patterns. In SAMSON, snapping tools offer a clean solution.
Why Snapping Helps
Snapping allows you to define exact values for translation and rotation—such as moving atoms by 0.5 Å increments or rotating molecules by 10° steps. This is especially useful for:
- Building symmetric structures (such as dimers or oligomers)
- Aligning fragments around a pivot atom
- Creating custom spatial arrangements for presentations
- Performing structure-based design tasks with geometric constraints
How Snapping Works in SAMSON
Snapping is integrated into SAMSON’s Move Editors—the Displacer, Local Move Editor, and Global Move Editor. It can be enabled from the quick access menu in the top-left corner of the viewport, or in:
Interface > Preferences > Editors > Snapping
Rotational Snapping Example
In the example below, a central structure is duplicated and each copy is rotated around a pivot atom using rotational snapping with the Global Move Editor. This results in accurate and symmetric placement:
How to Use It
- Select the objects you want to move.
- Activate the appropriate Move Editor (e.g., press K for the Global Move Editor).
- Specify your desired snapping increments (e.g., 10° for rotation or 0.5 Å for translation).
- Use the rotation or translation handles to perform the move. The editor displays the snapping result in real time.
This approach eliminates fiddling with mouse sensitivity or relying on visual estimation. It’s especially useful when repeating geometric transformations, where consistency is key.
A Few Tips
- Combine snapping with pivot control to rotate around specific atoms.
- You can undo any snapping operation via Edit > Undo.
- If you’re unsure which axis you’re snapping to, the color coding (red: X, green: Y, blue: Z) helps clarify directions.
Snapping provides a structured way to control spatial organization in your modeling workflows. It prevents accidental misalignments and helps create cleaner, more interpretable molecular scenes.
To learn more about snapping and other transformation tools in SAMSON, visit the official documentation: https://documentation.samson-connect.net/users/latest/moving-objects/
SAMSON and all SAMSON Extensions are free for non-commercial use. You can get SAMSON at https://www.samson-connect.net