On Ruelle's construction of the thermodynamic limit for the classical microcanonical entropy

Abstract

In this note we make a very elementary technical observation to the effect that Ruelle's construction of the thermodynamic limit of the classical entropy density defined with a regularized microcanonical measure actually establishes the thermodynamic limit for the entropy density defined with the proper microcanonical measure. At this stage a key formula is still derived from the regularized measures. We also show that with only minor changes in the proof the regularization of the microcanonical measure is actually not needed at all.