Creating molecular animations isn’t just about making visually engaging presentations. For researchers and designers in molecular science, it’s also a method to understand molecular interactions, spatial changes, and dynamics better. One frequent need during molecular modeling is to rotate a molecule or a group of atoms around its centroid – for example, to inspect interactions, highlight a specific conformation, or simply create smoother transitions in animations.
This is where SAMSON’s Rotate animation comes in handy. Built into the Animator, the Rotate animation allows you to rotate any selected group of particles around their geometric center, using a rotation vector that’s collinear with the Z-axis.
Why rotate around the centroid?
Suppose you’re modeling the effect of a ligand nearing a receptor site. If your visualization requires a subtle spin to examine potential docking conformations, rotating the entire group (rather than segmenting each portion) offers a clean, centralized movement. Rotating around the centroid ensures the particles behave as a coherent unit without unintended translations or spatial drifts.
How to apply the rotation
Here’s a quick step-by-step:
- Select the atoms or group you’d like to rotate. Selection is straightforward: simply use the standard selection tools in SAMSON (see the selection guide).
- In the Animation panel of the Animator, double-click on the Rotate animation effect.
- SAMSON will automatically add the Rotate effect between two keyframes. Move those keyframes to control the duration of the animation.
It’s that simple. The powerful thing is that the rotation vector always pivots around a fixed point — the centroid of your selection — making the movement predictable and stable. Perfect for a presentation showing symmetrical behavior, rotameric transitions, or comparative orientation.
Controlling the feel of the rotation
You can adjust the Easing curve to change how the rotation speed interpolates between your keyframes. Use easing to improve the visual quality of your animations — from linear speeds to smoother acceleration or deceleration effects that better simulate natural molecular dynamics.
A few extra tips
- Move the keyframes freely to adjust the duration of the rotation. Longer intervals slow the rotation down.
- You can combine Rotate with other effects like Move Atoms for more complex dynamics such as conformational change while rotating.
- If you use an older tutorial that mentions the “Animation menu,” remember this has been replaced with the Animation panel in the Animator — functionality is preserved, only the interface has changed.
To dig deeper into the Rotate animation and enhance your molecular design projects, visit the documentation page:
https://documentation.samson-connect.net/users/latest/animations/rotate/
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download and get started with SAMSON at https://www.samson-connect.net.