9413242 Prasad Dr. Prasad will elucidate the observed molecular composition of interstellar clouds through evolutionary chemical-dynamical models. In contrast to most previous equilibrium chemical models which assume fixed physical conditions, the proposed models will account for the fundamental interaction between the chemistry and dynamics. It is expected that the new models can better clarify: (1) The processes by which a given cloud can attain its present state; (2) how it will further evolve with time, and (3) the growing difficulties that are confronting current static pseudo-time-dependent gas phase chemical models. This award is under the Small Grants for Exploratory Research program at NSF.