# EMPLOYING DIFFUSION MONTE CARLO IN THE CALCULATION OF MINIMIZED ENERGY PATHS OF THE CH$_{3}^{+}$ + H$_{2}$ $\leftrightarrow$ CH$_{5}^{+}$ $\leftrightarrow$ CH$_{3}^{+}$ + H$_{2}$ REACTION AND ITS ISOTOPIC VARIANTS

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 dc.creator Hinkle, Charlotte E. en_US dc.creator McCoy, Anne B. en_US dc.date.accessioned 2011-07-12T17:29:00Z dc.date.available 2011-07-12T17:29:00Z dc.date.issued 2011 en_US dc.identifier 2011-RI-02 en_US dc.identifier.uri http://hdl.handle.net/1811/49374 dc.description Author Institution: Department of Chemistry, The Ohio State University, Columbus, OH 43210 en_US dc.description.abstract Protonated methane is presumed by astrochemists to be an important intermediate in the reaction CH$_3^+$ + HD $\rightarrow$ CDH$_4^+$ $\rightarrow$ CH$_2$D$^+$ + H$_2$ within the interstellar medium. Understanding this reaction can also help shed light on the observed nonstatistical H/D isotopic abundance in the isotopologues of CH$_3^+$ within the interstellar medium. Interestingly, based on kinetic studies, Gerlich and co-workers showed that all of the reactions in the series CH$_{3-n}$D$_n^+$ + HD $\rightarrow$ CH$_{4-n}$D$_{n+1}^+$ $\rightarrow$ CH$_{2-n}$D$_{n+1}^+$ + H$_2$ have identical net rate constants .{} This result is independent of the value of n. ~ In previous studies of CH$_5^+$, we have employed Diffusion Monte Carlo (DMC){} to study ground,{} and excited states.{}$^,${}$^,${}} By performing the simulation in Jacobi coordinates, we can use Adiabatic DMC{} to study the properties of the minimized energy paths of CH$_5^+$ and isotopologues. To determine the minimized energy path, we calculate the quantum zero-point energy and ground state wave function as a function of the distance between the center of mass of the H$_2$ group and the center of mass of the CH$_3^+$ group over a range from 0 to 6 $\mathrm{{\AA}}$. Over this range, we find 5 distinct regions of interaction, short range repulsion region, CH$_5^+$ complexation, short-range fragment interaction, long-range fragment interaction, and a region of no interaction between the two fragments. Interestingly, the range of H$_2$/CH$_3^+$ distances spanned by each of the regions is roughly independent of the number or location of the deuterium atoms. Interestingly, the range of H$_2$/CH$_3^+$ distances spanned by each of the regions is roughly independent of the number or location of the deuterium atoms. en_US dc.language.iso en en_US dc.publisher Ohio State University en_US dc.title EMPLOYING DIFFUSION MONTE CARLO IN THE CALCULATION OF MINIMIZED ENERGY PATHS OF THE CH$_{3}^{+}$ + H$_{2}$ $\leftrightarrow$ CH$_{5}^{+}$ $\leftrightarrow$ CH$_{3}^{+}$ + H$_{2}$ REACTION AND ITS ISOTOPIC VARIANTS en_US dc.type Article en_US