Themain idea behind objective structures is permutation invariance. Essentially, it says that the interchange
of atoms and molecules does not alter the energy of the system. What makes the theory of objective molecular
dynamics more general than the periodic molecular dynamics is the action of the group on the fundamental
domain. Whereas in periodic molecular dynamics, the group chosen is translations; for objective structures,
this can be generalized thereby producing a plethora of very interesting cases, even nonperiodic ones.