  The interplay between collective optical response and molecular static and
dynamic disorder is studied using simple effective Hamiltonians for an ensemble
of two-level emitters inside and outside a single-mode cavity. We model
environmental disorder by randomly modulating the molecular transition
frequencies and the coupling between the emitters and the electromagnetic
field. We also consider effects of intermolecular interactions and
orientational disorder. We investigate how these effects lead to new features
in the steady state absorption (outside the cavity), transmission spectra
(inside the cavity) and the yield of local molecular processes such as a
unimolecular reaction. Outside the cavity, the collective behavior is
manifested in the linewidth of the steady state absorption, the emission
spectrum, and the local chemical yield. Inside the cavity, however, the
collective behavior primarily determines the Rabi splitting. Effects of
intermolecular interactions under orientational disorder are also studied. For
the most part, for all types of disorder, if we increase disorder, we find a
reduction in the collective nature of the molecular response (smaller effective
N), and therefore, the Rabi splitting contraction occurs with orientational
disorder. Moreover, we find that static disorder is more destructive to
collective behavior than dynamic disorder.
