Ab initio investigation of the electronic structure of CeRh2Sb2

► CeRh2Sb2 known in simple tetragonal ST-CaGe2Ge2 and body centered BCT ThCr2Si2 types. ► Energy results from ab initio DFT calculations show a stabilization of ST versus BCT. ► Chemical bonding indicates strongest interactions in Rh-Sb layers. ► Antibonding Sb-Sb and Rh-Sb in BCT lead to instability and defects observed experimentally.