Fermi Statistics of Weakly Exicted Granular Systems in a Vibrating Bed I: Molecular Dynamics Simulations

Molecular dynamics simulations were carried out to test the thermodynamic theory of weakly excited, two-dimensional granular systems [Hayakawa and Hong, Phys. Rev. Lett. 78, 2764 (1997)], where granular materials are viewed as a collection of spinless Fermions. We first determine the global temperature T by fitting the steady state density profile to the Fermi distribution function, and then measure the center of mass, <z(T)>, and its fluctuations, <(\Delta z(T))^2> as a function of T. We find a fairly good agreement between theory and simulations, in particular, in the estimation of the temperature and the scaling behavior of <z(T)> and <(\Delta z(T))^2>.