  Band structures of pressure-induced CeNiGe3 and exotic BCS-like YNiGe3
superconductors have been calculated employing the full-potential local-orbital
code. Both the local density approximation (LDA) and LDA+U treatment of the
exchange-correlation energy were used. The investigations were focused on
differences between electronic properties of both compounds. Our results
indicate that the Ce-based system exhibits higher density of states at the
Fermi level, dominated by the Ce 4f states, in contrast to its non f-electron
counterpart. The Fermi surface (FS) of each compound originates from three
bands and consists of both holelike and electronlike sheets. The specific FS
nesting properties of only CeNiGe3 enable an occurrence of spin fluctuations of
a helicoidal antiferromagnetic character that may lead to unconventional
pairing mechanism in this superconductor. In turn, the topology of the FS in
YNiGe3 reveals a possibility of multi-band superconductivity, which can explain
the observed anomalous jump at Tc in its specific heat.
