An efficient physically motivated computational approach to multiband
superconductivity is introduced and applied to the study of the gap symmetry in
a heavy-fermion, UPd2Al3. Using realistic pairing potentials and accurate
energy bands that are computed within density functional theory,
self-consistent calculations demonstrate that the only accessible
superconducting gap with nodes exhibits d-wave symmetry in the A1g
representation of the D6h point group. Our results suggest that in a
superconductor with gap nodes the prevailing gap symmetry is dictated by the
constraint that nodes must be as far as possible from high-density areas