The vertical and adiabatic ionization energies of silicon carbide
  clusters, (SiC)$_n$, with n=1-12
  Silicon carbide (SiC) is one of the major cosmic dust components in
carbon-rich environments. However, the formation of SiC dust is not well
understood. In particular, the initial stages of the SiC condensation (i.e. the
SiC nucleation) remain unclear, as the basic building blocks (i.e. molecular
clusters) exhibit atomic segregation at the (sub-)nanoscale. We report vertical
and adiabatic ionization energies of small silicon carbide clusters, (SiC)$_n$
, n=2-12, ranging from 6.6-10.0 eV, which are lower than for the SiC molecule
($\sim$ 10.6 eV). The most favorable structures of the singly ionized
(SiC)$_n^+$, n=5-12, cations resemble their neutral counterparts. However, for
sizes n=2-4, these structural analogues are metastable and different cation
geometries are favored. Moreover, we find that the (SiC)$_5^+$ cation is likely
to be a transition state. Therefore, we place constraints on the stability
limit for small, neutral (SiC)$_n$ clusters to persist ionization through
(inter)-stellar radiation fields or high temperatures.
