The potential energy sequences of characteristic atoms were separated out by nine potential energy E-functions on the basis of larger experimental heats of formation of the L1 0 -AuCu and L1 2 -AuCu 3 compounds only. According to these potential energy sequences of characteristic atoms, the potential energies and heats of formation of disordered Au 1− x Cu x alloys were calculated by corresponding E-functions at 0 K; and the potential energies, heats of formation and critical T c -temperatures of the order-disorder transitions of L1 0 -AuCu, L1 2 -Au 3 Cu and L1 2 -AuCu 3 compounds, Au 3 Cu-, AuCu- and AuCu 3 -type ordered alloys with maximal ordering degrees were also calculated at 0 K. The results obtained by both the first and present parts of this investigation were compared. Comparing the results obtained by nine E-functions, the 5th E(x, 0, σ) function may be chosen for describing thermodynamic properties of the compounds, ordered and disordered phases and for establishing the phase diagram of the Au-Cu system in the future.