  We present results for the optical conductivity of Na2IrO3 within density
functional theory by including spin-orbit (SO) and correlation effects (U) as
implemented in GGA+SO+U. We identify the various interband transitions and show
that the underlying quasi-molecular-orbital nature of the electronic structure
in Na2IrO3 translates into distinct features in the optical conductivity. Most
importantly, the parity of the quasi-molecular orbitals appears to be the main
factor in determining strong and weak optical transitions. We also present
optical conductivity calculations for Li2IrO3 and discuss the similarities and
differences with Na2IrO3.
