Predictions of the $\mathrm{Pt}_{8}\mathrm{Ti}$ phase in unexpected systems*

The binary phase with 8:1 stoichiometry (prototype $\mathrm{Pt}_{8}\mathrm{Ti}$) has been observed in 11 systems. In every case, the elemental phase of A is face centered cubic (fcc) and is one of the group 10 (IUPAC nomenclature) elements (Pt, Pd, or Ni). High-throughput quantum mechanical energy calculations indicate, however, that the fcc group 9 elements Rh and Ir may also form the $\mathrm{A}_{8}\mathrm{B}$ phase with W. Extending the high-throughput search to the entire transition metal group (including La) reveals an unexpected wealth of new predictions---36 in total. Furthermore, several predictions occur in common alloy systems (e.g., Cu-Zn, Cu-Ni) which are believed to be well characterized. The results of a finite temperature simulation involving the cluster expansion method are presented for one system predicted to form the $\mathrm{A}_{8}\mathrm{B}$ phase, Rh-W. Computed order-disorder transitions suggests the phase may be experimentally realizable in Rh-W.