New thermodynamic potentials for surface science

J-potential belongs to the group of novel thermodynamic potentials for arbitrarily loaded solids. The article considers two modified forms of J-potential especially convenient for surface science. Definitions are given and fundamental equations are derived for bulk phases, interfaces, and interfacial lines. The application of J-potential is illustrated by deriving the Neumann and Gibbs equations for a number of interfaces meeting at a line, and the classical Young equation.