  The superconducting sesquicarbides R2C3 have noncentrosymmetric point group
symmetry Td. Spin-orbit coupling lifts the spin degeneracy of electronic bands
in the most of the Brillouin zone. Nevertheless, due to high symmetry, there
are a few directions along which the Fermi surfaces must touch. This leads to
the two-band effects in the superconducting state.
