Ab initio study on the ground states, phase stability, and mechanical properties of the Au–Pt system

For the equilibrium immiscible Au–Pt system, ground states are studied based on the results of the cluster expansion method combined with ab initio calculations. The obtained results show that there is no stable phase for the Au–Pt system at 0 K. The further obtained enthalpies of formation for hypothetical crystalline L12, D019, D03 structured Au3Pt and AuPt3, as well as L10 structured AuPt compounds also have positive values. Moreover, elastic constants are predicted from ab initio for the first time for the metastable L12 Au3Pt, AuPt3 and L10 AuPt compound. Finally, there is an imaginary phonon appearing in the obtained phonon spectra, implying an internal instability of the positions of the nuclear coordinates of the L12Au3Pt compound.