First-principles density functional theory (DFT) simulations were conducted using the Vienna Ab Initio Simulation Package (VASP) with projector-augmented wave (PAW) pseudopotentials provided by the code. An initial internal structural relaxation was performed with fixed experimental lattice parameters, using a planewave basis set with a kinetic energy cutoff of 500 eV, an 8×8×8 k-mesh, and an energy convergence threshold of 10 -7 eV. The Perdew-Burke-Ernzerhof (PBE) exchangecorrelation functional was used for this relaxation. For band structure calculations, the modified Becke-Johnson (mBJ) exchange-correlation functional was employed, including spin-orbit coupling. The pseudopotentials for Ag, Au, and Se/Te accounted for 11, 11, and 6 valence electrons, respectively.