  A combination of theoretical calculation and the experimental synthesis to
explore the new ternary compound is demonstrated in the Sr-Pt-Bi system. Since
Pt-Bi is considered as a new critical charge-transfer pair for
superconductivity, it inspired us to investigate the Sr-Pt-Bi system. With a
thorough calculation of all the known stable/metastable compounds in the
Sr-Pt-Bi system and crystal structure predictions, the thermodynamic stability
of hypothetical stoichiometry, SrPtBi2, is determined. Followed by the
high-temperature synthesis and crystallographic analysis, the first ternary
bismuthide in Sr-Pt-Bi, SrPtBi2 was prepared and the stoichiometry was
confirmed experimentally. SrPtBi2 crystallizes in the space group Pnma (S.G.
62, Pearson Symbol oP48), which matches well with theoretical prediction using
an adaptive genetic algorithm (AGA). Using first-principles calculations, we
demonstrate that the orthorhombic structure has lower formation energies than
other 112 structure types, such as tetragonal BaMnBi2 (CuSmP2) and LaAuBi2
(CuHfSi2) structure types. The bonding analysis indicates the Pt-Bi
interactions play a critical role in structural stability. The physical
properties measurements show the metallic properties with low electron-phonon
interactions at the low temperature, which agrees with the electronic structure
assessment.
