Showing papers on "Potential energy surface published in 1977"
TL;DR: In this article, a method of calculating the intrinsic reaction coordinate starting at a saddle point is proposed, which is used in combination with the analytical evaluation of the energy gradient for the calculation of the reaction coordinate on an ab initio potential energy surface.
Abstract: A practical method of calculating the intrinsic reaction coordinate starting at a saddle point is proposed. The method has been used in combination with the analytical evaluation of the energy gradient for the calculation of the reaction coordinate on an ab initio potential energy surface. The reaction coordinates are obtained for the HNC to HCN isomerization and the SN2 exchange reaction involving H−+CH4→CH4+H−.
748 citations
TL;DR: In this paper, a semiclassical expression for bimolecular rate constants for reactions which have a single activation barrier is obtained in terms of the "good" action variables of the (classical) Hamiltonian that are associated with the saddle point region of the potential energy surface.
Abstract: A semiclassical expression for bimolecular rate constants for reactions which have a single activation barrier is obtained in terms of the “good” action variables of the (classical) Hamiltonian that are associated with the saddle point region of the potential energy surface. The formulae apply to non-separable, as well as separable saddle points.
149 citations
TL;DR: In this article, the dynamics of the reaction O+H2(v) →OH+H is studied by means of three dimensional classical trajectory calculations on an LEPS potential energy surface.
Abstract: The dynamics of the reaction O+H2(v) →OH+H is studied by means of three dimensional classical trajectory calculations on an LEPS potential energy surface. Rate constants are calculated for the two cases in which the H2 molecule is initially in the v=0 and v=1 vibrational state. In the temperature range 298–1000 °K these rates are fit very well by the formulas (cm3 molecule−1 sec−1) k=2.81T×10−14 exp(−4279/T) and k=4.65T×10−14 exp(−1868/T). The calculated value of k at 300 °K is 2.8×10−14 cm3 molecule−1 sec−1 which is below the upper bound established by Birely [J. H. Birely, J.V.V. Kasper, F. Hai, and L. A. Darnton, Chem. Phys. Lett. 31, 220 (1975)]. The branching ratio Γ, defined as the ratio of the rates for populating the v′=1 and v′=0 state of OH when H2 is initially in the v=1 state is also calculated and fit by the expression Γ=2.3 exp(196/T). The value at 300 °K is 4.4.
119 citations
TL;DR: It is found that the out-of-plane metal displacement in pentacoordinate heme systems is due to both the restricted size of the porphyrin hole and the "1-3" steric interaction between the axial ligand and the heme nitrogens.
Abstract: The contribution of the porphyrin skeleton to the potential energy surface metalloporphyrins is calculated by the semiempirical method of quantum mechanical extension of the consistent force field to eta electron molecules. This calculation makes it possible to correlate the observed structure of metalloporphyrins with the strain energy of the porphyrin skeleton. It is found that the out-of-plane metal displacement in pentacoordinate heme systems is due to both the restricted size of the porphyrin hole and the "1-3" steric interaction between the axial ligand and the heme nitrogens. The main components of the active site of hemoglobin are simulated by a histidine-heme-oxygen system. The energy surface of this system provides a quantitative explanation for the control of ligand binding by hemoglobin. It is shown that the heme acts as a diaphragm, designed to provide simultaneous binding to the histidine and the sixth ligand under the steric requirements of the 1-3 interactions. The dependence of the hemoglobin potential surface on the distance between the proximal histidine and the heme plane is evaluated for the R and T states, using the calculated heme potential and the observed energy of heme-heme interaction.
94 citations
TL;DR: In this paper, the authors derive and show the utility of an approximate theory of chemical dynamics based on a generalized Franck-Condon factor for the analysis of collinear exoergic atom-diatom reactions.
Abstract: We derive and show the utility of an approximate theory of chemical dynamics based on a generalized Franck–Condon factor. We begin by showing how the general expression for the transition matrix for an electronically adiabatic reaction may be rewritten in terms of a transition between two surfaces through the use of a quasiadiabatic representation. This exact transition matrix may be reduced to a Franck–Condon overlap integral in a variety of ways, and one possible sequence of approximations for accomplishing this reduction is outlined. We neglect terms due to virtual transitions to excited electronic states, make a Born–Oppenheimer approximation, neglect terms involving gradients of the nuclear wavefunction (low kinetic energy approximation), and finally make a Franck–Condon approximation. The overlap is then evaluated for the special case of collinear exoergic atom–diatom reactions for the purpose of studying product state vibrational distributions in these reactions. The evaluation is done approximately by using physical arguments to estimate the general appearance of the reagent and product quasiadiabatic surfaces, and assuming separable solutions to the Schrodinger equation on each surface. The overlap integral is then further approximated by expanding the integrand about the nuclear configuration of maximum overlap. This enables us to obtain a simple analytical result for the product state distribution, using either harmonic or Morse oscillator vibrational wavefunctions. We then use the resulting expressions to study the dynamics of the collinear F+H2(D2) and H(D)+Cl2 reactions. In both applications we find that the Franck–Condon overlap is capable of a qualitatively correct description of the product state distributions, including dependence on reagent translational energy, mass ratios, and various features of the potential energy surface. Furthermore, a physical description of the origin of a dynamic threshold effect in the F+H2(D2) reaction is provided, as is a simple interpretation of the role of potential energy release behavior in the determination of product state distributions.
86 citations
TL;DR: In this paper, it is pointed out that it is more advantageous to express the Franck-Condon factors in terms of the gradient of the final state potential energy surface at the equilibrium geometry of the initial electronic state.
Abstract: In the customary calculation of vibrational intensity distribution in electronic spectra of polyatomic molecules, the Franck-Condon factors are expressed in terms of the difference of the equilibrium geometries of the initial and the final state. It is pointed out that it is more advantageous to express the Franck-Condon factors in terms of the gradient of the final state potential energy surface at the equilibrium geometry of the initial electronic state. The ionization and excitation of the NH3 molecule are considered to illustrate this fact. Although the change in geometry is known accurately in this case, rather poor Franck-Condon factors are obtained with the customary harmonic method. Remarkably enough, even the use of anharmonic potential energy functions, though rather laborious, does not improve the situation. The reason for this failure is discussed. Expanding, on the other hand, the final state potential energy around the initial state equilibrium geometry, we obtain satisfactory Franck-Condon ...
76 citations
TL;DR: In this article, a model potential for gas-solid interactions has been used to investigate the dynamics of recombination of two atoms initially adsorbed on a solid surface, where the rigid surface restriction is relaxed and one or more surface atoms are allowed to move interacting with the adorbed atoms.
Abstract: A model potential for gas–solid interactions has been used to investigate the dynamics of recombination of two atoms initially adsorbed on a solid surface. In the spirit of Polanyi’s investigation into the effect of the potential energy surface on the dynamics of gas‐phase reactions, a range of gas–solid potential energy surfaces has been constructed. Classical trajectories have been used to study the dynamics of reactions on those surfaces. It has been found that many of the rules postulated by Polanyi for energy requirements and disposal mechanisms for gas‐phase systems are applicable also to the case of recombination of adsorbed atoms to form a gas‐phase molecule. Previous work assumed a rigid surface providing a static background potential in which the adsorbed atoms moved. An extension of this model is described in which the rigid surface restriction is relaxed and one or more surface atoms are allowed to move interacting with the adsorbed atoms. Using this potential the rigid surface model is shown to be a good approximation for describing many aspects of recombination dynamics.
75 citations
TL;DR: In this article, a multi-structure valence-bond calculation was performed to determine the potential energy surface governing the reaction Li + HF → LiF + H. The results for both linear and non-linear nuclear geometries are presented.
Abstract: Ab initio multi-structure valence-bond calculations have been performed to determine the potential energy surface governing the reaction Li + HF → LiF + H. Results for both linear and non-linear nuclear geometries are presented. The system is a prototype for many heavier alkali metal plus hydrogen halide reactions which have been studied using the crossed molecular beams technique. The ab initio valence-bond results are improved by applying corrections, within the framework of the orthogonalized Moffitt (OM) method, for the atomic errors present. The orbital basis set used was of double zeta quality, and was augmented by some extra orbitals. Preliminary calculations on the neutral and ionic diatomic species were performed to ensure the adequancy of the valence-bond structure basis sets used and care was taken to ensure that the basis sets provided an adequate description of F–, HF– and LiF–. The endoergicity of the reaction, ignoring the zero-point vibrational energies, was predicted by the ab initio and OM methods to be 5.8 and 2.5 kcal mol–1 respectively, as compared with the experimental value of 2.6 kcal mol–1. Besides the ground state potential energy surface, several surfaces for excited electronic states have been calculated and are presented. The relationship of the ground state potential energy surface to the reactive cross section, and its variation with energy, is discussed. The ground and excited state potential energy surfaces are compared with previously proposed models and a mechanism for the production of alkali metal ions in hyperthermal alkali metal atom–hydrogen halide collisions is proposed.
65 citations
TL;DR: In this article, the effects of model dependence and statistical correlation upon the determination of a potential energy surface from the spectroscopic data for isotopic H2-Ar van der Waals complexes, are critically examined.
Abstract: The effects of model-dependence and statistical correlation upon the determination of a potential energy surface from the spectroscopic data for isotopic H2–Ar van der Waals complexes, are critically examined. The new potential thus obtained for this system has the correct theoretical long-range behaviour, and yields predicted differential scattering cross-sections and orbiting resonance energies in good accord with experiment. It is also shown that the secular equation method previously applied to H2+ inert gas complexes may also be successfully used to calculate the properties of much more strongly anisotropic species, such as HCl–Ar.
62 citations
TL;DR: In this article, a double zeta basis set of contracted Gaussian functions was used in conjunction with moderately large (2120 configurations) configuration interaction (CI) techniques to predict the least-motion insertion reaction of singlet methylene into molecular hydrogen.
Abstract: The least-motion insertion reaction of singlet methylene into molecular hydrogen is forbidden in the sense of Woodward and Hoffmann and has been predicted to involve a barrier height of approximately 27 kcal/mol. Here ab initio electronic structure theory has been applied to the non-least-motion features of the same potential energy surface. A double zeta basis set of contracted Gaussian functions was used in conjunction with moderately large (2120 configurations) configuration interaction (CI) techniques. For an initial C/sub s/ point group approach theory predicts no barrir or activation energy at all. This result is illustrated with the aid of contour maps showing several cuts through the potential energy hypersurface. It is also noted that the single determinant self-consistent field (SCF) method does not properly describe several of the main features of this concerted non-least-motion pathway.
56 citations
TL;DR: In this article, a potential energy surface of the collision dynamics of energy transfer processes was calculated by means of three-dimensional classical trajectories of collision dynamics, which consists of a London-Eyring-Polanyi-Sato (LEPS) potential function for short-range interactions and a partial point charge, dipole-dipole function for long-range interaction.
Abstract: Rate coefficients are calculated for the energy‐transfer processes that ocuur when HF(v1,J1) molecules collide with HF(v2, J2) molecules. Three‐dimensional classical trajectories of the collision dynamics of these energy‐transfer processes were calculated by means of a potential energy surface, which consists of a London–Eyring–Polanyi–Sato (LEPS) potential function for the short‐range interactions and a partial‐point‐charge, dipole–dipole function for long‐range interactions. This energy surface was used to predict an equilibrium geometry of the HF dimer. From the trajectory calculations it was predicted that the v→v energy‐transfer processes occur by means of Δv=±1 transitions and that the rate coefficients for the processes HF(v)+HF(v=0) →HF(v−1)+HF(v=1) decrease with increasing vibrational quantum number v. A calculation of the v→v rate for the reaction HF(v=1)+HF(v=1) →HF(v=0)+HF(v=2) indicates a value of 1.2×1013 cm3 mol−1 s−1 at 300 K. This process corresponds to near‐resonant vibration‐to‐vibratio...
TL;DR: In this paper, the authors used double zeta (DZ) quality and DZ augmented by polarization functions to study the CH(2Π)+H2→CH3 and CH(4Σ−)+H 2→CH2(3B1)+H reactions using ab initio molecular electronic structure theory.
Abstract: The CH(2Π)+H2→CH3 and CH(4Σ−)+H2→CH2(3B1)+H reactions have been studied using ab initio molecular electronic structure theory. Basis sets used were of double zeta (DZ) quality and DZ augmented by polarization functions. For the insertion reaction, the least motion barrier height is quite high, ∼75 kcal/mole. However, nonleast motion pathways are much more favorable, involving little or no barrier. In both respects this potential energy surface is analogous to that for the methylene insertion CH2(1A1)+H2→CH4. The quartet abstraction has a sizeable barrier, ∼11 kcal, associated with it, in analogy with the triplet methylene abstraction CH2(3B1)+H2→CH3+H.
TL;DR: In this paper, the potential energy surface in the non-reactive region has been determined theoretically for the H2-H2 system, which consists of a nonorthogonal configuration interaction calculation using the individual SCF orbitals of the separate molecules.
Abstract: The potential energy surface in the non-reactive region has been determined theoretically for the H2-H2 system. The procedure consists of a non-orthogonal configuration interaction calculation using the individual SCF orbitals of the separate molecules. The potential function is expressed as a 5-term sum of Legendre functions, and analytical expressions are given for the R dependence of the terms. The calculated depth of the spherically averaged Van der Waals well is -2·96 meV, which is in essentially complete agreement with the experimental value of -3·00 meV. the position of the minimum is at 3·49 A both theoretically and experimentally. The value of C 6 for dispersion forces obtained in this calculation is 12·97 a.u.
TL;DR: In this article, detailed three-dimensional quasiclassical trajectory calculations were performed for the reaction Cl+H2(0,J) →HCl+H on a semi-empirical LEPS potential energy surface.
Abstract: Detailed three‐dimensional quasiclassical trajectory calculations were performed for the reaction Cl+H2(0,J) →HCl+H on a semiempirical LEPS potential energy surface Calculations were carried out for initial vibrational state v=0, rotational states J=0–4, and collision energies E between threshold and 120 kcal/mole From the trajectory calculations we obtained reaction probabilities Pr(v=0,J,E,b) as a function of impact parameter b and initial values of J and E; reaction cross sections Sr(v=0,J,E) as a function of initial J and E; detailed rate constants k0,J and total rate constants kt in the temperature range 250–600°K, and the partitioning of energy and angular distribution of the products for different initial conditions Thermal rate constants were compared with results of other trajectory studies of this system, with results of transition state theory calculations, and with experimental results The trajectory rate constants of the present study were found to be in good agreement with experimental
TL;DR: In this article, it was shown that a termolecular, sixcentre reaction path for bond exchange among hydrogen molecules is energetically accessible, whereas there appears to be no bimolecular four-centre path.
Abstract: Ab initio electronic structure calculations show that a termolecular, six-centre reaction path for bond exchange among hydrogen molecules is energetically accessible, whereas there appears to be no bimolecular, four-centre path. Our best SCF calculation for hexagonal H6 finds the minimum potential energy lies about 39 kcal mol–1 below the 2H2+ 2H asymptote, or about 69 kcal mol–1 above the 3H2 asymptote. The optimum distance between neighbouring hydrogen atoms is only 0.99 A. This calculation employs ten orbitals (two s, three p, five d functions) on each hydrogen atom, with configuration interaction including all single and double excitations and an approximate correction for quadruple excitations. Calculations using less extensive SCF basis sets are also reported which give the zero point energy for the eleven nondissociative vibrational modes of hexagonal H6 and the potential energy profile along the reaction coordinate for the H6→ 3H2 dissociation. Other geometrical configurations of H6 are treated using the simple “diatomics-in-molecules” approximation. This gives good results for the hexagonal isomer (∼16 kcal mol–1 above our best ab initio energy) and indicates that only hexagonal H6 lies low enough to serve as a transition state for the six-centre reaction.Comparisons with approximate ab initio results for larger Hn polygons give an improved estimate for the cohesive energy of metallic hydrogen. It is also shown that H6 is the only H4m+ 2 system for which a concerted bond exchange reaction can occur. This illustrates the need to supplement orbital symmetry correlations with energetic criteria.
TL;DR: In this paper, the authors used classical trajectories on a realistic model potential energy surface (approximating one dissociation channel of CD_3Cl) driven by an external force to model infrared multiphoton dissociation.
TL;DR: In this paper, large-scale configuration interaction calculations of the potential energy surface of Li3 are described, and the major prediction which emerges is that triangular configurations are more stable than linear ones, with the 2B2 and 2A1 states having different equilibrium geometries but essentially the same energies.
Abstract: Large-scale configuration interaction calculations of the potential energy surface of Li3 are described. The major prediction which emerges is that triangular configurations are more stable than linear ones, with the 2B2 and 2A1 states having different equilibrium geometries but essentially the same energies. It is found that the most stable linear configuration is symmetric, unlike the prediction of restricted Hartree-Fock calculations. A fit of our calculated surface to a semi-empirical LEPS function is presented.
20 Jun 1977-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this paper, the theory of the coupling between anharmonic v (XH) and v(XH..Y) modes of a hydrogen-bonded complex developed in part II is extended so as to make explicit allowance for the effect of varying hydrogen bond length on the electron distribution of the XH molecule.
Abstract: The theory of the coupling between anharmonic v (XH) and v (XH. .Y) modes of a hydrogen-bonded complex developed in part II is extended so as to make explicit allowance for the effect of varying hydrogen bond length on the electron distribution of the XH molecule. Sufficient experimental data are available on the temperature dependence of the infrared spectrum of Me 2 O . HC1 to enable the form of the potential energy surface to be deduced. The effective potential curves governing the hydrogen bond vibration in the ground and first excited state of the v (XH) vibration are constructed. It is found that the Me 2 O . HC1 complex is 14 pm shorter in the upper state than in the lower, which has important consequences for the structure of the vibration-rotation bands associated with vibrational Franck-Condon transitions. The shortening is much less pronounced in Me 2 O . DC1. The theory provides strong support for the interpretation of the broad v (XH) bands of hydrogen bonded species in terms of v (XH) +/- nv (XH .. Y) combination bands, and demonstrates the close connection between the infrared spectroscopic anomalies and the Ubbelohde effect.
TL;DR: The vertical detachment energy of NO2− at its equilibrium geometry was 2.66 eV as discussed by the authors, where the highest occupied molecular orbital was of a 1-symmetric symmetry.
Abstract: The equations‐of‐motion (EOM) method was used to calculate the detachment energy of NO2−, including correlation and relaxation effects. Enough of the SCF‐level potential energy surface of NO2− was calculated to compute the thermodynamic electron affinity of NO2. The 2A1 potential surface of NO2 was obtained by adding the computed vertical detachment energy to the potential surface of NO2− at the corresponding geometry where the highest occupied molecular orbital was of a1 symmetry. The calculated vertical detachment energy of NO2− at its equilibrium geometry was 2.66 eV. Using the calculated potential energy surfaces and the reported values for the vibrational energy differences between NO2 and NO2−, the thermodynamic electron affinity of NO2 was calculated to be 2.25 eV, which compares very well with Lineberger’s experimental value of 2.36±0.1 eV.
TL;DR: In this paper, the CI surface of Tsapline and Kutzelnigg is extended to smaller H2He separations, and the ab initio values are fit to a Legendre series in cosγ retaining the first three (even) terms with the coefficients given as analytic functions of R and r to facilitate semiclassical scattering computations.
TL;DR: In this paper, anomalous structure in the interaction potential is discussed and the singlet He*−H2 potential energy surface is calculated for the AIP with respect to the He* −H2 energy surface.
Abstract: Calculations are reported for the singlet He*−H2 potential energy surface. Anomalous structure in the interaction potential is discussed. (AIP)
TL;DR: In this article, the generalized Brillouin theorem is used to construct an optimization procedure for MCSCF functions by iterative contracted CI calculations, with special attention paid to the MO transformation step in each iteration.
Abstract: The generalized Brillouin theorem is used to construct an optimization procedure for MCSCF functions by iterative contracted CI calculations. Special attention is paid to the MO transformation step in each iteration. In this method the MCSCF calculation may easily be augmented by a restricted CI calculation involving a configuration set which is uniquely determined by the trial function. An application to the calculation of the potential energy surface for linear LiH2 in the reaction LiH + H⇆Li + H2 leads to the conclusion that this restricted CI is necessary, in order to obtain satisfactory results for the potential energy barrier in this reaction.
01 Jan 1977
TL;DR: In this article, the authors present a survey of the state of the art in the field of artificial intelligence and artificial intelligence, focusing on the following topics: Artificial Intelligence and Artificial Intelligence.
Abstract: Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
TL;DR: In this paper, an analytical function for the potential energy surface of ozone is presented, which is based on the so-called surface energy function of the ozone molecule, and is used to estimate the energy of ozone.
Abstract: (1977). An analytical function for the potential energy surface of ozone. Molecular Physics: Vol. 34, No. 4, pp. 1185-1188.
TL;DR: In this paper, the potential energy surface for the reaction N++ H2→ NH++ H was analyzed for C 2v geometries and the 3B2 surface is strongly repulsive while the 3A2 surface has a shallow minimum.
Abstract: Ab initio configuration interaction calculations using Dunning's gaussian basis set are reported for the potential energy surface for the reaction N++ H2→ NH++ H. For the collinear approach of N+ to H2 the 3Σ– surface has a shallow minimum and the 3Π surface is repulsive. For C2v geometries the 3B2 surface is strongly repulsive and the 3A2 surface has a shallow minimum. The 3B1 surface has a deep well which is not adiabatically accessible at low relative energies. An avoided crossing in Cs symmetry between the 3A″ surfaces correlating with the 3A2 and 3B1 surfaces gives an adiabatic route to the deep potential well, but trajectory hopping is thought to be significant except at the lowest relative energies. Preliminary work on the fitting of an analytic function to attractive surfaces is discussed.
TL;DR: Using a functional form based on rotated Morse curves, cubic splines are used to fit the Shavitt-Stevens-Minn-Karplus (SSMK) potential surface for the collinear H+H2 reaction as mentioned in this paper.
Abstract: Using a functional form based on rotated Morse curves, cubic splines are used to fit the Shavitt–Stevens–Minn–Karplus (SSMK) potential surface for the collinear H+H2 reaction. The fit obtained by this method is shown by contour maps and difference maps to be excellent. The deviations which do occur are shown to result from the limitations of the method but also from an error in the SSMK function. Classical trajectories carried out on the spline‐fitted surface show good agreement with the results obtained from the analytical SSMK surface, including a point‐by‐point matching of most of the individual trajectories. The reactivity bands and total reaction probability agree closely with the two methods. The spline‐fitted potential function is more economical to use than the analytical function and is easily adjusted to give different surface features, which may be varied in an independent manner.
TL;DR: In this article, a threshold kinetic energy of 6.4762 kcal/mole (0.2808 eV) is determined for all possible combinations of H, D, and T, and reaction probabilities are determined in terms of the mass-dependent skew of the potential surface and differences in zero-point vibrational energy.
Abstract: Exchange in the hydrogen atom–molecule reaction is investigated via classical collinear dynamics on the Yates–Lester potential energy surface. A threshold kinetic energy of 6.4762 kcal/mole (0.2808 eV) is determined. Exchange probabilities are found to be, in general, slightly less than those obtained using the energy surface of Shavitt, Stevens, Minn, and Karplus. Energy banding is observed and discontinuities in the transition region are attributed to snarled trajectories. Reaction probabilities for all possible combinations of H, D, and T are determined. Isotopic variations in reaction probability are explained in terms of the mass‐dependent skew of the potential surface and differences in zero‐point vibrational energy.
TL;DR: In this paper, a potential energy hypersurface for the adiabatic process C2H5*⇄H+C2H4 is derived using the STO-3G self-consistent field method.
Abstract: A potential energy hypersurface for the adiabatic process C2H5*⇄H + C2H4 is derived. The potential energy at configurations corresponding to C2H5* is calculated using the STO–3G self-consistent field method. The C2H4 region is formulated from available semi-empirical information. The continuous potential energy surface is conceived as an interpolation between these arrangements. The lowest energy reaction path and general surface features are fitted to a general analytical form for use in dynamical calculations.
TL;DR: An analytical potential energy surface has been devised which is suitable for a dynamical study of the reaction C(3P) + O2(3Σ g -) → CO(1Σ+) + O(1D) … (1) as discussed by the authors.
Abstract: An analytical potential energy surface has been devised which is suitable for a dynamical study of the reaction C(3P) + O2(3Σ g -) →CO(1Σ+) + O(1D) … (1). An average triplet surface derived from scattering data on O(3P) + CO(1Σ+) has been used to deduce intersections with the singlet surface. A classical dynamical study of reaction (1) has been carried out with the inclusion of non-adiabatic transitions at the intersections. The probability of non-adiabatic transitions is calculated to be small, in agreement with experiment. The internal energy distribution of CO(1Σ+) has been calculated and shows a vibrational population inversion with a maximum at υ′ ∼ 14. This is also in qualitative agreement with experiment. The calculated rate constant for reaction (1) at 300 K is 1·92 × 10-11 cm3 mole-1 s-1 which is 26 per cent less than the most recent experimental estimate.
TL;DR: In this article, the problem of determining the most adequate calculation parameters in the multiple scattering Xα method is investigated in the PF4 radical case and a full geometry optimization of the radical is made using overlapping and non-overlapping atomic spheres and the corresponding spin density distribution in the various regions is calculated.
Abstract: The problem of determining the most adequate calculation parameters in the multiple scattering Xα method is investigated in the PF4 radical case. A full geometry optimization of the radical is made using overlapping and non-overlapping atomic spheres and the corresponding spin density distribution in the various regions is calculated. Comparisons with both SCF LCAO results and experiment show that a very reasonable description of the structure and electronic properties of the radical can be derived from the calculations using overlapping atomic spheres.