collection of systems
of atoms (or molecules)
which are used for the description of an individual system.
Time averages for the individual system
can be expressed by averaging over the systems
of the collection (ensemble) at a fixed time.
Refer to this page:
Note: If a company/institute/site doesn't want to present its own
information in nanodic.com, it can sent one e-mail to firstname.lastname@example.org.