Realistic selfconsistent calculations of unconventional superconductivity in
a heavy-fermion material are reported. Our calculations for UPd2βAl3β start
from accurate energy band dispersions that are computed within the local
spin-density functional theory and provide Fermi surfaces in agreement with
experiment. Using physically motivated, realistic pairing potentials it is
shown that the superconducting gap has two lines of nodes around the z-axis,
thus exhibiting d-wave symmetry in the A1gβ representation of the D6hβ
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.Comment: 4 pages and 3 figures (two color figures