2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/146944A statistical treatment of finite unbound systems in the presence of collective motions is presented and applied to a classical Lennard-Jones Hamiltonian, numerically simulated through molecular dynamics. In the ideal gas limit, the flow dynamics can be exactly re-casted into effective time-dependent Lagrange parameters acting on a standard Gibbs ensemble with an extra total energy conservation constraint. Using this same ansatz for the low density freeze-out configurations of an interacting expanding system, we show that the presence of flow can have a sizeable effect on the microstate distribution.7 pages, 4 figuresStatistical MechanicsNuclear Theorytext