Precision Control for Molecular Structures with SAMSON Move Editors

Moving molecular structures accurately is a critical part of molecular modeling. Whether you’re fine-tuning the positioning of fragments, arranging assemblies, or preparing systems for simulations, you often need to rotate and translate atoms with surgical precision. This is where SAMSON’s Move Editors become incredibly useful.

Move Editors in SAMSON provide intuitive and powerful tools to manipulate objects in your model. Importantly, these tools allow for both local and global transformations, snapping, and even custom pivot points, which help you maintain control without fiddling with complex scripts.

What Are Move Editors?

Move Editors are interactive tools you can activate in the SAMSON viewport to directly translate and rotate selected objects. SAMSON includes three built-in Move Editors:

  • Displacer – quick 2D movement in the plane of the screen
  • Local Move Editor – move relative to the object’s local axes
  • Global Move Editor – move along global XYZ axes

Each editor can be accessed from the left menu or via keyboard shortcuts:

  • D for Displacer
  • M for Local Move
  • K for Global Move

Move with Confidence: Snapping and Precise Control

One of the frustrations molecular modelers face is accidentally misplacing components when using mouse-only manipulation. Move Editors in SAMSON allow you to enable snapping for both rotation and translation. For example, you can snap rotational steps to 10° or translational steps to 0.5 Å, avoiding errors and saving time.

Rotating around an axis with snapping

The rotation and translation widgets are color-coded for clarity (e.g., red for X, green for Y, blue for Z). Options like trackball rotation, plane translation, and direct axis manipulation give you flexibility depending on how you need to pivot your molecules.

Rotating Fragments with a Custom Pivot Point

A particularly useful feature is the ability to define a pivot point when using the Global Move Editor. This is crucial when you want to rotate a fragment around a specific atom rather than the geometric center. By setting the snapping and using the right pivot, you can maintain symmetry or precisely generate rotated copies of a subunit.

Rotating a fragment

Use It Immediately with Visual Feedback

Each Move Editor action provides real-time visual feedback, and you can cancel any operation by pressing Esc. Plus, all operations are undoable using Edit > Undo, giving you freedom to explore different configurations safely.

When Should You Use Each Move Editor?

  • Displacer: When you want to quickly change location in 2D space (ideal during live simulations).
  • Local Move Editor: When working on single fragments or adjusting torsions.
  • Global Move Editor: When aligning with the global frame or copying structures symmetrically.

These tools are particularly handy for educational settings, protein engineering, coarse-grained modeling, and when building complex supramolecular assemblies. You’ll find they remove the guesswork from molecular transformations.

Learn More

For a full overview and more examples (including video tutorials), visit the official SAMSON documentation page on moving objects.

SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at www.samson-connect.net.

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