  The origins of rapid dynamical slow down in glass forming liquids in the
growth of static length scales, possibly associated with identifiable
structural ordering, is a much debated issue. Growth of medium range
crystalline order (MRCO) has been observed in various model systems to be
associated with glassy behaviour. Such observations raise the question about
the eventual state reached by a glass former, if allowed to relax for
sufficiently long times. Is a slowly growing crystalline order responsible for
slow dynamics? Are the molecular mechanisms for glass transition in liquids
with and without MRCO the same? If yes, glass formers with MRCO provide a
paradigm for understanding glassy behaviour generically. If not, systems with
MRCO form a new class of glass forming materials whose molecular mechanism for
slow dynamics may be easier to understand in terms of growing crystalline
order, and should be approached in that manner, even while they will not
provide generic insights. In this study we perform extensive molecular dynamics
simulations of a number of glass forming liquids in two dimensions and show
that the static and dynamic properties of glasses with MRCO are different from
other glass forming liquids with no predominant local order. We also resolve an
important issue regarding the so-called Point-to-set method for determining
static length scales, and demonstrate it to be a robust, order agnostic, method
for determining static correlation lengths in glass formers.
