Average Velocity

The Average velocity analysis follows the mean velocity magnitude of a selected group along a path. It is useful for dynamical trajectories and for quickly spotting bursts of motion or unusually quiet regions.

Adding the plot

1. Open Path Analyzer.
2. Choose Average velocity in Observable.
3. Choose a Path.
4. Define the Group to analyze.
5. Click Add Velocity Series or Add Velocity Distribution.

Inputs

• One atom-containing selection is required.
• The chosen path must expose velocity data for the selected atoms.

Views

• Velocity series: follow the mean velocity magnitude over the path.
• Velocity distribution: inspect the sampled distribution.

Key equation

For a selected atom set \(\mathcal{A}\), Path Analyzer computes the mean velocity magnitude at frame \(t\) as

\[ \bar{v}(t)=\frac{1}{|\mathcal{A}|}\sum_{a\in\mathcal{A}}\|\mathbf{v}_a(t)\| \]

Card settings

• Units can be switched after creation between Auto, pm/fs, A/ps, and m/s.

Tip

• Use average velocity for trajectories with meaningful dynamical information.
• Compare it with Average force when you want to connect driving forces and resulting motion.