RECENT DEVELOPMENTS IN MODELING GAS-PHASE AND GRAIN-SURFACE CHEMISTRY

We discuss some new results in our modeling program of the chemistry of assorted evolutionary stages leading to star formation. We first consider new topics in gas-phase chemistry, including the formation of the new organic molecules detected with the Green Bank Telescope and the chemistry of newlyobserved molecular anions. Although interstellar chemistry occurs both in the gas phase and on the surfaces of dust particles, there are still severe difficulties in constructing models with both types of processes. We discuss some current work on improving our treatment of surface chemistry. Moreover, the role of PAH's has been largely ignored in recent years, and some new results concerning this topic are presented. Finally, the advent of the ALMA era is beginning to force modelers such as ourselves to include both small-scale heterogeneity and dynamics in their approaches. A hydrodynamic model of the diverse chemistry that occurs in the formation of a protostellar core is discussed