A molecular animation can become hard to read when every part of a structure moves at once. A receptor may drift while you are trying to show a ligand, or a stable reference region may shift between moments in a docking or assembly presentation. The viewer then has to work harder to tell which movement matters.
Hold atoms offers a simple way to keep a selected group of particles in place during a chosen span of an animation. That can make the moving part of a molecular scene easier to follow without requiring you to remove the rest of the structure from view.
Use a stable reference to clarify motion
Think of a molecular presentation as a visual explanation: the moving elements show what changes, while a fixed reference helps the audience understand where that change occurs. For example, when presenting a docking animation, holding a surrounding group of atoms in place can help viewers focus on the changing position of the docked structure. In an assembly presentation, a stationary part can provide context as another part moves.
This is a presentation technique, not a claim about molecular behavior. Holding atoms in an animation keeps their positions fixed between its two frames; it should not be confused with applying a physical restraint or changing the results of a molecular simulation.
Set up the Hold atoms animation
- Select the particles whose positions should remain fixed. Choose the group that provides useful context for the motion you want to show.
- Add the animation. In the Animator, open the Animation panel and double-click Hold atoms.
- Position the keyframes. The selected particles are held at fixed positions between the animation’s two keyframes. Move those keyframes as needed to choose when the hold begins and ends in your presentation.
It can help to decide on the visual story before adjusting timing: identify what should stay still, what should move, and the interval during which the stable reference is useful. Then preview the presentation and check that the hold covers the intended portion. If the reference needs to remain fixed for a different part of the sequence, adjust the keyframes rather than changing the selection without first checking what the animation is meant to hold.
A small staging choice with a practical payoff
Keeping a reference group still can reduce visual clutter and make a comparison easier to explain. It is especially useful when the point of a presentation is not simply that a structure moves, but how one part moves relative to a recognizable, stationary context. Used selectively, Hold atoms helps preserve that context while leaving the motion you want to discuss visible.
For a complementary animation that moves selected particles, see Move atoms. For the full instructions and examples, visit the Hold atoms documentation.
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