Showing papers on "Potential energy surface published in 1980"
TL;DR: In this paper, the authors derived the classical Hamiltonian of a polyatomic system in terms of these coordinates and their conjugate momenta for the general case of an N atom system with a given nonzero value of the total angular momentum.
Abstract: The reaction path on the potential energy surface of a polyatomic molecule is the steepest descent path (if mass‐weighted Cartesian coordinates are used) connecting saddle points and minima. For an N‐atom system in 3d space it is shown how the 3N‐6 internal coordinates can be chosen to be the reaction coordinate s, the arc length along the reaction path, plus (3N‐7) normal coordinates that describe vibrations orthogonal to the reaction path. The classical (and quantum) Hamiltonian is derived in terms of these coordinates and their conjugate momenta for the general case of an N atom system with a given nonzero value of the total angular momentum. One of the important facts that makes this analysis feasible (and therefore interesting) is that all the quantities necessary to construct this Hamiltonian, and thus permit dynamical studies, are obtainable from a relatively modest number of ab initio quantum chemistry calculations of the potential energy surface. As a simple example, it is shown how the effects o...
1,296 citations
TL;DR: Barrier heights and transition state geometries have been calculated for the reaction OH+H2→H2O+H using large scale POLCI wave functions (based on GVB wave functions using basis sets of up to triple zeta valence plus double zeta polarization quality) as discussed by the authors.
Abstract: Barrier heights and transition state geometries have been calculated for the reaction OH+H2→H2O+H using large scale POL‐CI wave functions (based on GVB wave functions using basis sets of up to triple zeta valence plus double zeta polarization quality). The saddle point geometry is found to be coplanar and to resemble OH+H2 as expected because of the large exoergicity (∼16 kcal/mole) of the reaction. The OH distance of the OH moiety is essentially the same as for the OH molecule, while the HH distance of the H2 moiety is 0.10 A (∼14%) longer than for H2. The distance from the O to the near hydrogen of the H2 moiety is 0.35 A (∼36%) longer than for the H2O molecule. The HOH angle is 98° and the H2 moiety is tilted from collinearity with the O atom by 15° toward the H of the OH moiety. The calculated barrier height using a [4s3p2d/3s2p] basis set is 6.2 kcal/mole. Transition state theory calculations (including a Wigner tunneling correction) using the theoretically computed surface predict rate constants which are in excellent agreement with experiment over the temperature range of 300–2000 °K.
203 citations
TL;DR: In this article, a highly accurate ab initio surface for the interaction potential of the system HeH2 is computed, which is essentially of CI type, but different calculations with different basis sets are performed for SCF and intrasystem correlations and (2) the intersystem correlation.
Abstract: A highly accurate ab initio surface for the interaction potential of the system HeH2 is computed. The method applied is essentially of CI type, but different calculations with different basis sets are performed for (1) the SCF and intrasystem correlations and (2) the intersystem correlation. The former is corrected for basis superposition errors (counterpoise method) and the latter is corrected by inclusion (or simulation) of triply substituted configuration. For either calculation basis saturation tests are performed, a criterion for the interbasis being that it accounts correctly for the van der Waals constants C6,C8 and C10 and their anisotropies on three successive levels of sophistication. The calculations cover the range from R=1.5a0 (0.8 A) to R=∞ for the He–H2 distance, and r=0.9 a0 to 2.0 a0 for the H–H distance and the orientation angles 0 °, 45 °, 90 °.
178 citations
TL;DR: In this paper, Liu and Siegbahn used an accurate potential energy surface, based on the ab initio calculations of Liu, and calculated rate constants for the reactions D+H2→DH+H and H+D2→HD+D and compared to measured values.
Abstract: Rate constants are calculated for the reactions D+H2→DH+H and H+D2→HD+D and compared to measured values. An accurate potential energy surface, based on the ab initio calculations of Liu and Siegbahn, was used. Rates were calculated using both conventional transition state theory and canonical variational theory. In the former, the generalized transition state dividing surface is located at the saddle point; in the latter it is located to maximize the generalized free energy of activation. We show that, in the absence of tunneling corrections, locating the generalized‐transition‐state dividing surface variationally has an important quantitative effect on the predicted rate constants for these systems and that, when tunneling is included, most of the effect of using a better dividing surface can be included in conventional transition state theory for these systems by using a consistent transmission coefficient for quantal scattering by the vibrationally adiabatic potential energy curve. Tunneling effects ar...
144 citations
TL;DR: In this paper, a simplified theoretical model was constructed in terms of the intrinsic reaction coordinate (IRC) and normal coordinates perpendicular to it for the four-centered elimination reaction CH3CH2F→HF+CH2CH2.
Abstract: The mechanism of energy disposal along the reaction pathway was discussed in relation to the characteristic features of potential energy surface. A simplified theoretical model was constructed in terms of the intrinsic reaction coordinate (IRC) and normal coordinates perpendicular to it. Ab initio MO calculations with the split‐valence basis set were carried out for the four‐centered elimination reaction CH3CH2F→HF+CH2CH2. The energy gradient method was used to optimize the stationary points on the potential surface and to trace IRC as well as to calculate the force constants. The origin of vibrational enhancement of HF in the reaction product was interpreted as the result of interchange of the main components of IRC in a local region where the IRC curvature is large.
143 citations
TL;DR: In this paper, the three dimensional potential energy hypersurface for Li+HF→LiF+H has been studied at the selfconsistent field (SCF) and configuration interaction (CI) levels of electronic structuretheory with a medium-sized basis set that included polarization functions.
Abstract: The three dimensional potential energy hypersurface for Li+HF→LiF+H has been studied at the self‐consistent field (SCF) and configuration interaction (CI) levels of electronic structuretheory with a medium‐sized basis set that included polarization functions. The ’’corner’’ of the reaction channel was first mapped by calculation of a lattice of points, then further calculations were carried out to characterize selected points along the minimum energy pathway more precisely. The classical reaction endothermicity was 2.9 kcal/mole, but with zero‐point corrections, the reaction was found to be exothermic by 1.7 kcal/mole. As the Li atom approaches the diatomic, it first forms a bent complex with 4.5 kcal/mole of stabilization energy before reaching the transition state. The latter, also bent with an angle of 74° was located in the exit channel and is predicted to be 10 kcal/mole above the reactants. Force constants, vibrational frequencies, and zero‐point energies of the complex and the transition state were calculated. After applying zero‐point corrections to the transition state, the threshold energy for reaction was reduced to 6.4 kcal/mole, which will probably be further reduced to ∼4 kcal by higher order correlation effects. Our results were compared with previous theoretical efforts and with qualitative theories concerned with the transition state angle and its exit bias. A qualitative discussion of the dynamics over the surface emphasizing interrelationships between the translational, vibrational energy and the LiFH angle ϑ is also presented.
135 citations
107 citations
TL;DR: In this article, a combined analysis of the state-to-state differential cross sections of the j = 0 to j= 0 and the j=0 to j = 2 transition of D2+Ne was performed in a crossed nozzle beam apparatus with time-of-flight analysis of scattered particles using the pseudorandom chopper method.
Abstract: Differential cross sections for the rotational excitation from j=0 to j=2 of D2 scattered by Ne have been measured at an energy of E=84.9 meV. The experiments have been performed in a crossed nozzle beam apparatus with time‐of‐flight analysis of the scattered particles using the pseudorandom chopper method. A detailed analysis of the experimental data which are peaked in the backward direction showed that they are mainly sensitive to the repulsive part of the pure anisotropic potential. From a combined analysis of the state‐to‐state differential cross sections of the j=0 to j=0 and the j=0 to j=2 transition of D2+Ne and the j=0 to j=1 transition of HD+Ne previously measured, the complete potential energy surface for the hydrogen–neon system is obtained using the coupled states method. The anisotropic contribution varies from 37% of the isotropic part in the repulsive region (2.4 A) to 12% in the attractive region (3.5 A). The results differ from the other potential models derived for this system from calc...
101 citations
TL;DR: A complete configuration interaction (CI) ground state surface for the H3+ system has been calculated using 5S and 3(Px,Py,Px) basis functions at each center.
Abstract: A complete configuration interaction (CI) ground state surface for the H3+ system has been calculated using 5S and 3(Px,Py,Px) basis functions at each center A total of 650 nuclear geometries has been considered which makes the new surface appropriate not only for scattering calculations, but also for the evaluation of the vibrational–rotational spectrum of the H3+ molecule Significant deviations are found from the analytic Giese and Gentry potential used in many previous theoretical studies, especially for large and small nonequilibrium H–H separations which are important for vibrational excitation of the H2 molecule Vibrational–rotational excitation cross sections have been calculated in the rotational sudden approximation where the vibrational degree of freedom is treated exactly by solving seven vibrationally coupled radial equations The use of the new surface leads to increased vibrational excitation compared to previous calculations utilizing the same scattering approximation and to excellent ag
90 citations
TL;DR: In this article, an approximate quantum mechanical theory of reactive scattering is presented and applied to the H+H2 reaction in three dimensions, where the vibrational states are treated in a fully coupled manner.
Abstract: An approximate quantum mechanical theory of reactive scattering is presented and applied to the H+H2 reaction in three dimensions. Centrifugal sudden and rotational sudden approximations are made in each arrangement channel, however, vibrational states are treated in a fully coupled manner. Matching of arrangement channel wave functions is done where the arrangement channel centrifugal potentials are equal. This matching is particularly appropriate for collinearly favored reactions. Integral and differential cross sections are calculated for the H+H2 reaction for H2 in the ground and first excited vibrational states. These calculations employ the Porter–Karplus potential energy surface mainly to allow for comparisons with previous accurate and approximate quantal and quasiclassical calculations.
87 citations
TL;DR: In this article, a detailed study was made of the effects on the calculated barrier height and saddle point geometry of the O(3P)+H2→OH+H using large scale POLCI wave functions (based on GVB wave functions using basis sets of up to triple zeta valence plus double zeta polarization quality).
Abstract: Barrier heights and transition state geometries have been calculated for the reaction O(3P)+H2→OH+H using large scale POL‐CI wave functions (based on GVB wave functions using basis sets of up to triple zeta valence plus double zeta polarization quality). A detailed study was made of the effects on the calculated barrier height and saddle point geometry of (i) basis set, (ii) choice of orbitals, and (iii) choice of reference configurations. Calculations using a [4s3p2d/3s2p] basis lead to a collinear saddle point with rHH=0.92 A and rOH=1.23 A with a corresponding barrier height of 12.5 kcal/mole. There are two surfaces which connect the reactants with the products: one of 3A′ symmetry and one of 3A″ symmetry (these correspond to the two degenerate components of the 3Π state in collinear geometries). In the transition state region, the 3A′ surface has a steeper bending curve than the 3A″ surface leading to significantly different reaction rates on the two surfaces.
TL;DR: In this paper, the potential energy surfaces of the water cation H2O+ have been studied using configuration interaction techniques and double-zeta quality basis sets augmented with polarization functions have been used throughout.
Abstract: Potential energy surfaces of the water cation H2O+ have been studied using configuration–interaction techniques. Double‐zeta quality basis sets augmented with polarization functions have been used throughout. The theoretical C2v equilibrium conformations of the ? 2B1, ? 2A1, and ? 2B2 states have been determined. The 2A1 potential surface has a minimum for the linear conformation of the ion, and the 2B2 surface has its minimum at an H–O–H angle of 55.7 °. The vibronically coupled 2A1 ‐ 2B2 (1 2A′ ‐ 2 2A′) set of states has been examined at Cs conformations in both the adiabatic and diabatic representations. This coupling, although too weak to eliminate the C2v minimum in the 2B2 potential surface, is expected to perturb the lower‐lying 2B2 vibronic levels. Two dissociation pathways for the 2B2 H2O+ ion (C2v and Cs) are partially characterized.
TL;DR: In this paper, close coupled calculations of scattering amplitudes have been carried out for H2-H2 collisions for a new ab initio potential energy surface, treating the hydrogen molecules as true vibrotors.
Abstract: Close‐coupled calculations of scattering amplitudes have been carried out for H2–H2 collisions for a new ab initio potential energy surface, treating the hydrogen molecules as true vibrotors. The amplitudes were inserted into the kinetic theory expressions for integral and transport cross sections and used to compute (1) the elastic scattering of (j=0, v=0) para‐hydrogen for relative velocities between 1000 and 2500 m/sec; (2) the viscosity differences of ortho‐ and para‐hydrogen for temperatures less than 25 °K; and (3) the thermal diffusion ratio of ortho‐ and para‐hydrogen for temperatures between 50 and 150 °K. The agreement with experiment is highly satisfactory and provides a thoroughgoing test of the new potential energy surface.
TL;DR: The structures of four isomeric forms of the model SiH2LiF have been investigated by ab initio molecular orbital theory as mentioned in this paper, and the two most stable forms are suggested to be the SiH 2Li+F− ion pair and the H2Si : FLi complex, analogous to the similar structures previously found for carbenoids.
TL;DR: In this article, a potential energy function has been derived for the ground state surface of C2H2 as a many-body expansion, which reproduces the energy, geometry and harmonic force field of C 2H2.
Abstract: A potential energy function has been derived for the ground state surface of C2H2 as a many-body expansion. The 2- and 3-body terms have been obtained by preliminary investigation of the ground state surfaces of CH2([Xtilde] 3 B 1) and C2H([Xtilde] 2Σ+). A 4-body term has been derived which reproduces the energy, geometry and harmonic force field of C2H2. The potential has a secondary minimum corresponding to the vinylidene structure and the geometry and energy of this are in close agreement with predictions from ab initio calculations. The saddle point for the HCCH-H2CC rearrangement is predicted to lie 2·530 eV above the acetylene minimum.
TL;DR: In this article, the potential energy surface for the lowest singlet states for fluoroformaldehyde HFCO is calculated using the ab initio SCF method, at these optimized geometries, CI calculations have been performed using the 6−31G basis sets.
Abstract: The potential energy surface for the lowest singlet states for fluoroformaldehyde HFCO is calculated. The geometries of the reactant HFCO, the elimination products HF+CO and the isomerization product FCOH as well as the transition states have been determined with the ab initio SCF method. At these optimized geometries, CI calculations have been performed using the 6‐31G basis sets. (AIP)
TL;DR: In this article, the authors apply the diagrammatic manybody perturbation theory through third order in the correlation energy to the interaction potential between He and a rigid LiH molecule and derive an analytic representation of the potential surface in terms of orthogonal polynomials.
Abstract: The diagrammatic many‐body perturbation theory is applied through third order in the correlation energy to the interaction potential between He and a rigid LiH molecule. The ab initio calculations are used to derive an analytic representation of the potential surface in terms of orthogonal polynomials. Several different basis sets are employed to demonstrate the sensitivity of the energies to the computational techniques. The resulting potential surfaces are highly anisotropic with respect to the LiH center‐of‐mass and allow for a weak binding (∼7 meV) of the He to the Li end of the LiH axis.
TL;DR: In this paper, three dimensional quantum mechanical calculations are carried out for the reactive scattering of D+H2→DH+H on the ab initio potential energy surface calculated by Liu and Siegbahn and fitted by Truhlar and Horowitz.
Abstract: Three dimensional quantum mechanical calculations are carried out for the reactive scattering of D+H2→DH+H on the ab initio potential energy surface calculated by Liu and Siegbahn and fitted by Truhlar and Horowitz. The differential and total cross sections as well as the S matrix elements are obtained from the adiabatic distorted wave method. Threshold energy, cross sections and product distributions over final states are all in good agreement with experimental measurements. Results are also compared with the corresponding ones obtained on the Porter–Karplus and the Yates–Lester semi‐empirical surfaces.
TL;DR: In this paper, a model potential energy function for the ground state of H2CO has been derived which covers the whole space of the six internal coordinates and leads to the prediction that there should be a metastable singlet hydroxycarbene HCOH which has a planar trans structure and an energy of 2·31 eV above that of equilibrium formaldehyde.
Abstract: A model potential energy function for the ground state of H2CO has been derived which covers the whole space of the six internal coordinates. This potential reproduces the experimental energy, geometry and quadratic force field of formaldehyde, and dissociates correctly to all possible atom, diatom and triatom fragments. Thus there are good reasons for believing it to be close to the true potential energy surface except in regions where both hydrogen atoms are close to the oxygen. It leads to the prediction that there should be a metastable singlet hydroxycarbene HCOH which has a planar trans structure and an energy of 2·31 eV above that of equilibrium formaldehyde. The reaction path for dissociation into H2 + CO is predicted to pass through a low symmetry transition state with an activation energy of 4·8 eV. Both of these predictions are in good agreement with recently published ab initio calculations.
TL;DR: In this article, the authors test several approximate theories of thermal rate constants against accurate quantal equilibrium rate constants for collinear bimolecular reactions governed by given potential energy surfaces.
Abstract: We test several approximate theories of thermal rate constants against accurate quantal equilibrium rate constants for collinear bimolecular reactions governed by given potential energy surfaces The systems considered are F+H2 and F+D2 for the Muckerman potential energy surface no 5 at 200–1200 K and H+F2, D+F2, and T+F2 for potential surface II of Jonathan, Okuda, and Timlin at 233–1260 K For F+H2, conventional transition state theory overestimates the accurate rate constant by factors of 29–34, with the largest errors at the lowest and highest temperatures Vibrationally adiabatic transmission coefficients or variational transition state theory decrease the error to factors of 12–13 at the lowest temperature and to a factor of 32 at the highest temperature The unified statistical model reduces the errors to a factor of 11 at the lowest temperature and a factor of 27 at the highest temperature For F+D2 the trends are similar but the errors in all the methods are smaller at all temperatures For H+F2 conventional transition state theory underestimates the rate constants by a factor of 056 at the lowest temperature with the error decreasing to 2% at the highest temperature Various formulations of vibrationally adiabatic transmission coefficients, in conjunction with either conventional or variational transition state theory, reduce the error to factors of 084–096 at the lowest temperature while not destroying the good agreement at the highest temperature The unified statistical theory seems to overestimate the recrossing correction for this reaction, though only by about 10% The results are similar for D+F2 and T+F2 except that the low‐temperature underestimates of the calculations without tunneling are not as severe The best theory, improved canonical variational theory with the Marcus–Coltrin path semiclassical adiabatic ground‐state transmission coefficient, reproduces the accurate quantal results for H+F2, D+F2, and T+F2 within 5% or better in every case for the whole temperature range
TL;DR: In this paper, a comparison of quantal and trajectory trajectories for vibrational energy transfer and dissociation in collinear atom-diatom collisions is made, and the quantal transition probabilities show higher thresholds than the trajectory ones, and then oscillate about the trajectory results.
Abstract: Quantal wave packet calculations and quasiclassical trajectory calculations are reported for vibrational energy transfer and dissociation in collinear atom–diatom collisions. The system considered has the masses of H+H2 and is modelled with an extended LEPS potential energy surface. The conditions considered are initial vibrational states n1=0,1, and 4 and initial relative translational energies up to 12 eV for the wave packet calculations and up to 13 eV for the trajectory calculations. This is higher in energy than previous comparisons of quantal and trajectory calculations. The quantal transition probabilities show higher thresholds than the trajectory ones, and then they oscillate about the trajectory results. The first and second moments of the final vibrational action are similar for both kinds of calculation.
TL;DR: Quasiclassical trajectory calculations for X+H2(0, 0) and H+X2( 0, 0), X=H, D, T at thermal energies have been carried out on the accurate SLTH potential energy surface; both collinear and three-dimensional results are considered.
Abstract: Quasiclassical trajectory calculations for X+H2(0, 0) and H+X2(0, 0), X=H, D, T at thermal energies have been carried out on the accurate SLTH potential energy surface; Both collinear and three‐dimensional results are considered. In three dimensions, the trends in reactivity are those which would be expected from energetic considerations (e.g., exoergicity) but are here explained in terms of simple dynamical effects. Trends in final properties, such as rotational distribution and differential cross sections are presented and explained.
TL;DR: In this paper, the strong coupling limit of the E⊗ζ Jahn-Teller effect was investigated and the high energy part of the JT band shape was shown to exhibit an oscillatory behaviour in this limit.
Abstract: The strong coupling limit of the E⊗ζ Jahn-Teller effect is investigated. The high energy part of the JT band shape is shown to exhibit an oscillatory behaviour in this limit. The oscillations are interpreted by adiabatic and Franck-Condon calculations as arising from the vibrational levels of the upper potential energy surface. A new measure of the coupling strength is proposed which is related to the excitation strength of these levels. It is shown to govern the approach of the exact band shape to the semiclassical limit.
TL;DR: In this article, the authors report accurate quantum mechanical reaction probabilities, rate constants, and activation energies for collinear T+HD→TH+D on an accurate potential energy surface, including tunneling contributions by two quantum mechanical and three semiclassical methods based on a vibrationally adiabatic treatment of reaction in the ground state.
Abstract: We report accurate quantum mechanical reaction probabilities, rate constants, and activation energies for collinear T+HD→TH+D on an accurate potential energy surface. We also report approximate calculations by conventional transition state theory, the unified statistical model, and three versions of variational transition state theory. We include tunneling contributions by two quantum mechanical and three semiclassical methods based on a vibrationally adiabatic treatment of reaction in the ground state. The most accurate approximate calculations for temperatures up to 1500 K are the improved canonical variational theory with Marcus–Coltrin path vibrationally adiabatic ground state (MCPVAG) transmission coefficient and the microcanonical variational theory with MCPVAG transmission coefficient. These two theories and the unified statistical theory with MCPVAG transmission coefficient are accurate within 41% for 400–2400 K but underestimate the rate constant by factors of 2.0 and 2.6 at 300 and 200 K, respectively. The two most accurate approximate theories overestimate the energy of activation for 300–1000 K by 0.46 kcal/mole. The unified statistical model with MCPVAG transmission coefficient produces slightly less accurate rate constants for 600–1500 K and more accurate ones at 2400 K. It overestimates the activation energy for 300–1000 K by only 0.40 kcal/mole.
TL;DR: In this paper, a new inversion method is developed which uses detailed vibrotational and total rate coefficient data in order to obtain the potential energy surface for a chemical reaction, which is applied to the reaction X+Cl2→XCl+Cl (X=Mu,H,D).
Abstract: A new inversion method has been developed which uses detailed vibrotational and total rate coefficient data in order to obtain the potential energy surface for a chemical reaction. The method is applied to the reaction X+Cl2→XCl+Cl (X=Mu,H,D). The philosophy of the method is to separate the dynamical effects due to the collinear and the noncollinear parts of the potential surface, which are then treated independently, and to reduce a large amount of experimental data to a few informative quantities. These are then related to a small number of potential surface parameters. This compaction of data is carried out in an iterative scheme starting from a potential surface assumed to be sufficiently similar to the correct one. In the present case, the collinear part of the potential surface is constrained to be of the extended LEPS variety with correct asymptotic properties and two adjustable Sato parameters. Information theoretic techniques are used to obtain the fraction of reactive reagents and then the vibro...
TL;DR: In this paper, the relative vibration-rotation product distributions for both potential energy surfaces and the differential cross sections are very similar as are the energy dependences of these quantities, in agreement with quasiclassical results.
Abstract: Vibrationally adiabatic distorted wave calculations of vibration-rotation product distributions and differential cross sections have been carried out for the reaction O(3 P) + H2(ν ⩽ 2, j, mj ) →OH (ν′ ⩽ 2, j′, mj′ ) + H. A LEPS potential energy surface of Johnson and Winter, and a fitted ab initio potential surface of Schinke and Lester have been used. The calculations have been performed over a range of translational energies close to the quasiclassical dynamical thresholds. The relative vibration-rotation product distributions for both potential surfaces and the differential cross sections are very similar as are the energy dependences of these quantities. Reactions for which ν →ν′ = ν are favoured over reactions for which ν →ν′ ≠ ν, in agreement with quasiclassical results. Initial vibrational excitation enhances reaction, in agreement with quasiclassical and experimental studies. The relative product state rotational distributions are unimodal, insensitive to the value of the initial rotational state...
TL;DR: In this paper, the I and I′ resonance series of O2 has been reexamined using high resolution for photons and electrons, and the photoelectron spectra on the resonances are predicted from the upper potential energy surface parameters and photoionization yield curve alone, without reference to the uncertain line shapes and widths.
Abstract: Autoionization from the I and I′ resonance series of O2 has been reexamined using high resolution for photons and electrons. Photoelectron spectra on the resonances are predicted from the upper potential energy surface parameters and photoionization yield curve alone, without reference to the uncertain line shapes and widths. Bond lengths are determined as 1.370±.005 A in I and 1.380±.005 A in I′ of O2.
TL;DR: In this article, the potential energy surface for the β-lactam amidic CN bond breaking in the 3-cephem + OH− reaction was investigated by using the ab initio Hartree-Fock method with a 9s6p/7s3p/3s basis set.
TL;DR: In this paper, the potential energy surface of β-lactam + OH − reaction was investigated using the ab initio Hartree-Fock method with the STO-3G basis set.
TL;DR: In this paper, a wave function was developed for the collinear 4-S+N2+N+NO+N(4S) reaction with ab initio exothermicity of 0.93 eV.
Abstract: The collinear 4Σ− pathway for the state‐specific O+(4S)+N2(X 1Σg+) →NO+(X 1Σ+)+N(4S) reaction has been surveyed with ab initio calculations. A ninety‐nine configuration, fifteen orbital multiconfiguration self‐consistent field (MCSCF) wave function, involving the use of a double‐zeta plus polarization one‐electron basis, was developed for the long range 4Σ− state. This long range 4Σ− state has the character of O++N2 for long RNO, or of N+NO+ for long RNN, and is for most geometries, the lowest, or 1 4Σ−, state. The ab initio exothermicity computed with the present wave function is 0.93 eV, compared to an accurate experimental value of 1.10 eV. The saddle‐point in the energy surface is 8.0 eV above O++N2, with critical values of R*NN=1.48±0.02 A and R*NO =1.38±0.02 A. These values are 0.38 and 0.32 A greater than the equilibrium bond lengths of N2(X 1Σg+) and NO+(X 1Σ+). The present wave function reproduces the experimental bond lengths of these two diatomics to within 0.01 A when the third atom is removed...