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Extensive ab initio calculations have been performed on the reaction N+3(P)+H21(Σ+g)NH+ (X 2Π)+H(2S), using complete-active-space self-consistent-field and multireference contracted configuration interaction methods. The 752 calculated energy points belonging to the 1 3A‘ surface were fitted to an analytical potential energy surface, with an average least-squares deviation of only 0.026 eV (2.5 kJ/mol). A key to this accurate fit of the surface, which does include minima as deep as 6 eV, is the use of R-n polynomials in the asymptotic region, and Rn polynomials in the deep minima regions. The calculated reaction endothermicity is 0.03 eV, after correcting for the differences in zero point vibrational energies. This is in agreement with the essentially thermoneutral reaction enthalpy, obtained in recent experiments. An important feature of the potential energy surface is the anisotropy in the reactant channel, arising from the ion–quadrupole interaction. [ABSTRACT FROM AUTHOR]

A quasiclassical trajectory study investigating the N++H2(D2)→NH+(ND+)+H(D) reactions has been performed. Two potential-energy surfaces differing only in their thermicities were employed. Both surfaces are based on the recent ab initio calculations for the N+(3P)+H2(1Σ+g)→NH+ (2Π)+H(2S) reaction by Wilhelmsson et al. Dynamics, forward–backward scattering, product energies, and trajectory lifetimes are discussed. Reaction cross sections and thermal rate constants are presented and compared with experimental results. In general, the agreement with experimental data is good. The thermicity of the reaction can, however, not be established by the trajectory calculations. [ABSTRACT FROM AUTHOR]

A low energy quasiclassical trajectory study has been performed on three potential energy surfaces, obtained by modifying the recent ground state ab initio potential energy hypersurface by Wilhelmsson et al. for the N+(3P)+H2(1Σ+g)→NH+ (2Π)+H(2S) reaction. The importance of explicit consideration of the asymptotic ion–induced dipole and ion–quadrupole interactions in the entrance channel is demonstrated. Reaction cross sections as a function of collision energy (approximately in the range 0.06–0.4 eV in c.m.) are presented. [ABSTRACT FROM AUTHOR]