  In low dimensions, the combined effects of interactions and quantum
fluctuations can lead to dramatically new physics distinct from that existing
in higher dimensions. Here, we investigate the electronic and optical
properties of CeIr$_{3}$B$_{2}$, a quasi-one-dimensional (1D) Kondo lattice
system, using $ab\ initio$ calculations. The Ce atoms in the hexagonal crystal
structure form 1D chains along the $c$-axis, with extremely short Ce-Ce
distances. The quasi-1D nature of the crystal structure is well reflected in
its electronic structure. Extremely flat bands emerge within the $ab$-plane of
the Brillouin zone, yielding sharp optical transitions in the corresponding
optical conductivity. Our calculations indicate that these prominent peaks in
the optical conductivity provide a clear signature of quasi-1D heavy fermion
systems.
