On the isoenthalpic-isobaric ensemble in classical statistical mechanics

Generalized ensemble theory is used to develop several fundamental formulae which describe the isoenthalpic-isobaric ensemble of classical statistical mechanics. The isoenthalpic-isobaric partition function is related to thermodynamics and averages for properties in the ensemble are expressed in terms of averages in the microcanonical ensemble. Mean square volume fluctuations in the ensemble are found to be simply related to the adiabatic compressibility and mean square kinetic energy fluctuations are found to be related to the isobaric heat capacity.