Title: CO2 packing polymorphism under confinement in cylindrical nanopores,
Abstract: We investigate the effect of cylindrical nano-confinement on the phase
behaviour of a rigid model of carbon dioxide using both molecular dynamics and
well tempered metadynamics. To this aim we study a simplified pore model across
a parameter space comprising pore diameter, CO2-pore wall potential and CO2
density. In order to systematically identify ordering events within the pore
model we devise a generally applicable approach based on the analysis of the
distribution of intermolecular orientations. Our simulations suggest that,
while confinement in nano-pores inhibits the formation of known crystal
structures, it induces a remarkable variety of ordered packings unrelated to
their bulk counterparts, and favours the establishment of short range order in
the fluid phase. We summarise our findings by proposing a qualitative phase
diagram for this model.