Adiabatic thermostatistics of the two parameter entropy and the role of Lambert’s W-function in its applications

A unified framework to describe the adiabatic class of ensembles in the generalized statistical mechanics based on Schwämmle–Tsallis two parameter (q,q′) entropy is proposed. The generalized form of the equipartition theorem, virial theorem and the adiabatic theorem are derived. Each member of the class of ensembles is illustrated using the classical nonrelativistic ideal gas and we observe that the heat functions could be written in terms of the Lambert’s W-function in the large N limit. In the microcanonical ensemble we study the effect of gravitational field on classical nonrelativistic ideal gas and a system of hard rods in one dimension and compute their respective internal energy and specific heat. We found that the specific heat can take both positive and negative values depending on the range of the deformation parameters, unlike the case of one parameter Tsallis entropy.