Thermodynamic Potentials of Small Separated Systems

Expressions for the thermodynamic potentials (TPs) of small systems are traditionally used in thermodynamics by analogy with TPs of ordinary macro-phases. This form of introducing TPs for small systems eliminates their specificity consisting in the presence of dimensional dependences for TP values and all other thermodynamic functions. To take into account the sizes of small systems in the traditional method of introducing TPs, it is necessary to explicitly reflect the presence of an interface and the associated heterogeneity of the internal local properties of a small system. The general case is discussed when dimensional dependences of TPs of small systems in limited volumes are introduced, with macroscopic concepts of the phase and the interface non-autonomy being preserved. Options are considered to introduce size dependences into TPs of small droplets and separated fluid phases inside pores.