Velocities

Velocities are associated with the "velocities" key in the model inputs, and must adhere to the following metadata schema:

Metadata for velocities

Metadata	Names	Description
keys	"_"	the keys must have a single dimension named "_", with a single entry set to 0. Velocities are always a metatensor.torch.TensorMap with a single block.
samples	["system", "atom"]	the samples must be named ["system", "atom"], since velocities are always per-atom. "system" must range from 0 to the number of systems given as an input to the model. "atom" must range between 0 and the number of atoms/particles in the corresponding system. If selected_atoms is provided, then only the selected atoms for each system should be part of the samples.
components	"xyz"	velocities must have a single component dimension named "xyz", with three entries set to 0, 1, and 2. The velocities are always 3D vectors, and the order of the components is x, y, z.
properties	"velocities"	velocities must have a single property dimension named "velocities", with a single entry set to 0.

At the moment, velocities are not integrated into any simulation engines.