Electronic structure of superconducting Lu2Ni3Si5 and its reference compound Y2Ni3Si5 by ab initio calculations

► Superconducting Lu2Ni3Si5 studied by LDA band structure calculations. ► Electronic structure of the non-superconducting Y2Ni3Si5 counterpart investigated. ► Similarity of 3D Fermi surfaces in the Lu- and Y-based compounds. ► Superconductivity in Lu2Ni3Si5 mainly due to small electron Fermi surface pockets. ► Ferromagnetic ground state excluded in Y2Ni3Si5 by fixed spin moment calculations.