The uniform phase space representation of product state distributions of elementary chemical reactions

Abstract

The uniform phase space (UPS) representation of translational or internal degrees of freedom of the products of a chemical reaction is presented. Procedures are developed to deal with cases in which the final state distribution is discrete or approximately continuous; extensions cover multidimensional distributions. Explicit realistic models are used to demonstrate these situations. In the UPS representation, the statistical or phase space distribution over product states is constant, yielding equal volumes of phase space for equal intervals along the coordinate in the UPS representation. As a consequence, an actual distribution over product states, cast into the UPS representation, becomes a direct measure of its deviance from a statistical distribution. The information content (in the information theoretic sense) is invariant under transformation to this representation, and its value can be readily approximated by a simple histogrammic procedure. Calculations for realistic model problems illustrate the superiority of the UPS representation of the energy disposal in elementary chemical reactions.