Model Hysteresis Dimer Molecule. II. Deductions from Probability Profiles

Abstract

The hysteresis dimer reaction of Part I is applied to test the Gibbs density-in-phase hypothesis for a canonical distribution at equilibrium. The probability distribution of variously defined internal and external variables is probed using the algorithms described, in particular the novel probing of the energy states of a labeled particle where it is found that there is compliance with the Gibbs’ hypothesis for the stated equilibrium condition and where the probability data strongly suggests that an extended equipartition principle may be formulated for some specific molecular coordinates. The possible ambiguity of internal variables as described in mesoscopic nonequilibrium thermodynamics (MNET) is very briefly discussed in relation to Hamiltonian variables, and a canonical distribution for a certain class of internal variables is observed and described, and plausible reasons outlined, where it is found that the always free dimer and atom particle kinetic energy distributions agree fully with Maxwell-Boltzmann statistics but the distribution for the relative kinetic energy of bonded atoms does not, even when all of these coordinates are not canonical variables. The principle of local equilibrium (PLE) commonly used in nonequilibrium theories to model irreversible systems is investigated through NEMD simulation at extreme conditions of bond formation and breakup at the reservoir ends in the presence of a temperature gradient, where for this study a simple and novel difference equation algorithm to test the divergence theorem for mass conservation is utilized, where mass is found to be conserved from the algorithm in the presence of flux currents, in contradiction to at least one aspect of PLE in the linear domain. It is concluded therefore that this principle can be a good approximation at best, corroborating previous purely theoretical results derived from the generalized Clausius Inequality which proved that the PLE cannot be an exact principle for nonequilibrium systems.