15min:
DIFFUSION MONTE CARLO CALCULATIONS OF MINIMUM ENERGY PATHS FOR THE ISOTOPIC VARIANTS OF THE CH3+ + H2 leftrightarrow CH5+ leftrightarrow CH3+ + H2 REACTION.

CHARLOTTE E. HINKLE, ANNE B. MCCOY, Department of Chemistry, The Ohio State University, Columbus, OH 43210.

Protonated methane is of interest to astrochemists due to its presumed importance as a reaction intermediate in the reaction involving CH3+ + HD within the interstellar medium. However, within the interstellar medium there is a nonstatistical H/D isotopic abundance observed for the isotopologues of CH3+. Kinetic studies performed by Gerlich and co-workers determined that the reactions \beginequation \mathrmCH3-nDn+ + HD rightarrow CH4-nDn+1+ rightarrow CH2-nDn+1+ + H2 \endequation have identical net rate constants regardless of the value of n. We have calculated zero-point corrected energies and wave functions of the CH3+ + H2 system and its deuterated analogs as functions of the center of mass separation between CH3+ and H2, R. We can divide these simulations into distinct ranges of R; long-range interactions, complexation, and intermediate distances. Analysis of the wave functions associated with these three ranges of R allows us to study how zero-point energy influences the approach geometries that are sampled during low-energy collisions.