ON THE KINETIC DESCRIPTION OF THE OBJECTIVE MOLECULAR DYNAMICS

In this paper, we develop a multiscale hierarchy framework for objective molecular dynamics (OMD), a reduced-order molecular dynamics with a certain symmetry, that connects it to the statistical kinetic equation, and the macroscopic hydrodynamic model. In the mesoscopic regime, we exploit two interaction scalings that lead, respectively, to either a mean-field type or to a Boltzmann-type equation. It turns out that, under the special symmetry of OMD, the mean- field scaling leads to a substantially simplified Vlasov equation that extinguishes the underlying molecular interaction rule, whereas the Boltzmann scaling yields a meaningful reduced model called the HOMO-energetic Boltzmann equation. At the macroscopic level, we derive the corresponding Euler and Navier-Stokes systems by conducting a detailed asymptotic analysis. The symmetry again significantly reduces the complexity of the resulting hydrodynamic systems.