In this study, we used the FP-LAPW technique based on density functional theory applied in WIEN2k code to examine structural, electronic, elastic, and thermoelectric properties of cubic double perovskite Rb2InBiX6 (X = Cl, Br) compounds. The structural stability was confirmed from tolerance factor, formation energy, phonon dispersion. exchange-correlation potentials LDA, GGA, mBJ, HSE were esti...