  We combine dynamical and non-equilibrium chemical modeling of evolving
prestellar molecular cloud cores, and explore the evolution of molecular
abundances in the contracting core. We model both magnetic cores, with varying
degrees of initial magnetic support, and non-magnetic cores, with varying
collapse delay times. We explore, through a parameter study, the competing
effects of various model parameters in the evolving molecular abundances,
including the elemental C/O ratio, the temperature, and the cosmic-ray
ionization rate. We find that different models show their largest quantitative
differences at the center of the core, whereas the outer layers, which evolve
slower, have abundances which are severely degenerate among different dynamical
models. There is a large range of possible abundance values for different
models at a fixed evolutionary stage (central density), which demonstrates the
large potential of chemical differentiation in prestellar cores. However,
degeneracies among different models, compounded with uncertainties induced by
other model parameters, make it difficult to discriminate among dynamical
models. To address these difficulties, we identify abundance ratios between
particular molecules, the measurement of which would have maximal potential for
discrimination among the different models examined here. In particular, we find
that the ratios between NH3 and CO; NH2 and CO; NH3 and HCO+ are sensitive to
the evolutionary timescale, and that the ratio between HCN and OH is sensitive
to the C/O ratio. Finally, we demonstrate that measurements of the central
deviation (central depletion or enhancement) of abundances of certain molecules
are good indicators of the dynamics of the core.
