Thermodynamic considerations on thermostats and Maxwell relations in steady sheared fluids

The role of two different definitions of temperature in nonequilibrium steady states (a kinetic one and a thermodynamic one) is examined in connection with thermostats used in nonequilibrium molecular dynamics to remove the dissipated heat in computer simulations of steady sheared fluids. The analysis is macroscopic, but it has also a microscopic root in information theory, and it deals with ideal gases and with dense fluids. The relevance of these temperatures and thermostats in the analysis of Maxwell relations following from nonequilibrium macroscopic thermodynamic potentials is explicitly studied. © 2011 Springer-Verlag.