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A method for calculating multiple long-range interaction potentials between an atom (C in this particular case), and closed-shell molecules is described. This method was recently utilized by Bettens and Collins [J. Chem. Phys. 114, 10342 (2001)] for determining capture rate coefficients for collisions of C ([sup 3]P[sub j]) and Ge ([sup 1]S[sub 0]) with unsaturated hydrocarbons. The method takes account of the physical size of the molecule and exactly treats the electrostatic interaction between the quadrupole of the atom and all electrostatic moments of the molecule. This method requires a molecular density matrix, which can be obtained from an ab initio calculation. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Studies the interpolated potential energy surface (PES) and reaction dynamics for oxygen. Brief description of the interpolation procedure used to construct the triplet PES; Main features of the triplet PES as indicated by the energy profiles along minimum energy paths for reactions; Ab initio methods.

An ab initio potential-energy surface for the ground doublet state of BH[sub 3][sup +] has been constructed at the QCISD(T)/6-311G(d,p) level of theory. Classical simulations of the collision between BH[sup +] and H[sub 2](D[sub 2]) and isotopic analogs show that the deep BH[sub 3][sup +] well gives rise to substantial "scrambling" of the hydrogen and deuterium atoms leading to BHD[sup +]+D, BD[sup +]+HD, and BD[sub 2][sup +]+H products. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have calculated the capture rate coefficients for collisions of C ([sup 3]P[sub j]) and Ge ([sup 1]S[sub 0]) with unsaturated hydrocarbons and compared them with the experiments of Husain and co-workers [Clary, Haider, Husain, and Kabir, Astrophys. J. 422, 416 (1994); Husain, Ioannou, and Kabir, Z. Phys. Chemie 203, 213 (1998)]. Our findings indicate (i) that all nine electronic surfaces for the C ([sup 3]P) reactions must contribute to the observed reaction rate coefficients, (ii) a central multipole approach is inappropriate for calculating the capture rate coefficients involving the larger hydrocarbons, (iii) the trends observed in the measured rate coefficients for the Ge and C reactions can simply be understood in terms of the physical size of the hydrocarbons, and (iv) the electrostatic interaction plays a significant role in the determination of capture rate coefficients for reactions involving C ([sup 3]P) and highly polar species as well as acetylene. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents corrections to the classical simulations of C + H[sub 3][sup +] collisions which were not performed with zero rotational angular momentum in the reactant H[sub 3][sup +]. Reduction of the total reaction cross section at low translational energy for zero rotational angular momentum in the reactant; Total cross section; Branching ratios for reactions.

Interpolated ab initio potential energy surfaces which describe abstraction and exchange reactions in collisions of hydrogen and water are reported. The electronic structure calculations are performed at the QCISD(T) level of theory, with an additivity approximation. A sufficiently large basis set is required to describe the Rydberg character of the electronic state for molecular configurations which are important for the exchange process. Classical and quantum dynamics calculations on the surfaces are presented. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]