Snapshots

BaseSnapshot([topology])	Simulation snapshot.
SnapshotDescriptor(contents)	Container for information about snapshots generated by an engine.

Trajectories

Trajectory([trajectory])

Simulation trajectory.

Dynamics Engine Functions

DynamicsEngine([options, descriptor])

Wraps simulation tool (parameters, storage, etc.)

Topologies

Topology(n_atoms[, n_spatial])

Topology is the object that contains all information about the structure of the system to be simulated.