2. Computational Details

We performed all calculations with the CASTEP code [29,30]. We employed generalized gradient approximation (GGA) [31] of density functional theory (DFT) within Perdew, Burke and Ernzerhof (PBE) exchange-correlation energy [32] through spin-polarized calculations of the addressed alloys. We employed ultrasoft pseudo-potential scheme with 600eV cut-off energy for Rh2MnX alloys. We have used 11x11x11 Monkhorst-Pack [33] k point sampling mesh considering the Broyden-Fletcher-Goldfarb-Shanno (BFGS) full geometry optimization algorithm [34-36]. The self-consistent convergence of total energy was fixed to a value of 5 x10-6 eV/atom. The maximum force was adjusted as 0.01 eV/Å where maximum displacement was kept to be as 5x10-4 Å under maximum stress with 0.02 GPa. The computed lattice parameters of the alloys were 6.16 Å, 6.38 Å, 6.33 Å, 6.28 Å and 6.05 Å for Rh2MnTi, Rh2MnZr, Rh2MnHf, Rh2MnzSc and Rh2MnZn, respectively. Fig. 1 shows the crystal structure of presently computed Rh2MnTi as a precursor of Rh2MnX alloys where Table 1. summarizes and compares the lattice constants of all calculated alloys. The crystal space group of the surveyed alloys are Fm-3m under cubic symmetry with space group number 225. In these alloys, Rh atoms occupy the 8c Wyckoff position (1/4, 1/4, 1/4) and the Mn and X atoms are at the 4a (0, 0, 0) and 4b (1/2, 1/2,1/2) positions, respectively. The resulting crystal exists with four interpenetrating face-centered cubic lattices, where the Y and Z atoms form an octahedral-coordinated rock-salt structure and the X atoms occupy the tetrahedral voids [25]. Similar to Rh2MnTi alloy, geometric conditions are also the same for the rest of other surveyed alloys of this study.