Articles you may be interested inTheoretical Compton profile anisotropies in molecules and solids. IX. Chemical bonding and 0-90 anisotropies in the firstrow diatomic hydrides AH J. Chem. Phys. 79, 2913 (1983); 10.1063/1.446113 Study of the electronic structure of molecules. XXII. Correlation energy corrections as a functional of the HartreeFock type density and its application to the homonuclear diatomic molecules of the second row atoms J. Chem. Phys. 60, 1288 (1974); 10.1063/1.1681193Study of the electronic structure of molecules. XXI. Correlation energy corrections as a functional of the HartreeFock density and its application to the hydrides of the second row atoms Hartree-Fock wavefunctions are presented for the LiH(X 12;+), BeH(X 22;+) BH(X 12;+) CH(X 2II ) NH(.~32;-), C?H(X2IIi), and H~(Xl2;+) molecules. These are the analytic 'self-consiste~t-field wa~e~ funct~ons obtamed from the sol~tJons of the Hartree-Fock-Roothaan equations. Large sets of Slater-;type functions centered on bot~ nuclel were used as the expansion basis, and extensive optimization of the orbital exponents has been carned out. The ~otal energies obtained for R.(exptl) are -7.98731, -15.15312, -~5.13~37, -38.27935, -54.9?8~6, :-,5.42083,. and -100.07030 hartrees, respectively, for the AH hy-d=ldes hsted above. The first lOmzation potentials, which are obtained from the Hartree-Fock energy differe~c.es between.AH and AH+ systems,. are 7. 02, 8.14, 8.45,10.08,12.82,11.44, and 14.54 eV, respectively. In addltl~n, potential curves, ~pectroscoplC constants, and c~rtain other energetic quantities are presented. C:u~e estlmat~s of the co;relatlo.n energy of the first-row hydndes are made and such quantities are compared wlthm t~e senes ~nd wlth thelr respecti:ve united and separated atoms. These results suggest that the changes m correlatlOn energy of AH relative to the correct united atom is independent of which hydride is involved and the change is small.

Both theoretical and experimental electron-impact total ionization cross sections of CF4, C2F6, and C3F8 are presented. The experimental cross sections have been measured as a function of incident electron energy T from threshold to 3 keV. A parallel plate condenser type apparatus was used. The molecular polarizability for C3F8 was empirically estimated to be α=10.6 Å3±0.8 Å3. Theoretical cross sections calculated from the binary-encounter-Bethe (BEB) method, which combines a modified form of the Mott cross section and the Bethe cross section, are compared with the experimental cross sections. The BEB cross sections calculated from correlated molecular wave functions with theoretical estimates for multiple ionization are about 10% higher than the experimental data at the peak for CF4, while they are in excellent agreement with the experimental data for C2F6 and C3F8. Our analysis shows that the BEB theory implicitly includes part of neutral dissociation, such as CF4→CF3+F, and hence tends to be an upper limit to the total ionization cross section. We found that the difference between our best theory for CF4 and the present experimental cross section exhibits a remarkable similarity to the shape of the recently measured cross section for neutral dissociation, though there is no a priori reason for the similarity. Owing to the large number of bound electrons, the correlation included in our wave functions for C2F6 and C3F8 is more limited than for CF4. Hence, we believe that for these two molecules the calculated cross sections are lower than the true BEB values, in spite of the apparent excellent agreement between the theory and the experiment.

Vibrational and rotational energy transfer rate coefficients are computed for hightemperature N 2 under conditions expected for re-entry into Earth's atmosphere at 10-12 km/s. The calculations utilized classical mechanics to simulate individual collisions of N 2 with N atoms and a quantum chemical potential energy surface to describe the interatomic forces between the the nitrogen atoms. The results demonstrate the importance of exchange reactions, which result in multiquantum jumps in vibration and rotation level. Nomenclature A= pre-exponetial parameter in Arrhenius expression for reaction rate coefficient D e = diatomic molecule dissociation energy (measured from the bottom of the potential well) E = total electronic energy in the solution of the Schrödinger equation. E A = activation energy in Arrhenius expression for reaction rate coefficient E rel = relative collision energy E vib = average vibrational energy H = Hamiltonian operator in the Schrödinger equation J = initial rotation quantum number J' = final rotation quantum number K = reaction rate coefficient k B = Boltzmann constant n = temperature-dependence parameter in Arrhenius expression for reaction rate coefficient N = nitrogen atom N a , N b , N c = labels for specific nitrogen atoms in N 3 N 2 = diatomic (molecular) nitrogen N 3 = the set of 3 nitrogen atoms to describe the N 2 + N collisions R = separation between atoms in a diatomic molecule R e = equilibrium bond distance in a diatomic molecule S = collision cross section t = time T ave = average temperature in 2-T models T electron = electron temperature T electronic = electronic state temperature T int = internal temperature (i.e., vibration plus rotation) T kin = kinetic temperature

The N + N2 exchange rate is calculated using a time-dependent quantum dynamics method on a newly determined ab initio potential energy surface (PES) for the ground 4A" state. This ab initio PES shows a double barrier feature in the interaction region with the barrier height at 47.2 kcal/mol, and a shallow well between these two barriers, with the minimum at 43.7 kcal/mol. A quantum dynamics wave packet calculation has been carried out using the fitted PES to compute the cumulative reaction probability for the exchange reaction of N + N2(J=0). The J -K shift method is then employed to obtain the rate constant for this reaction. The calculated rate constant is compared with experimental data and a recent quasi-classical calculation using a LEPS PES.Significant differences are found between the present and quasiclassical results. The present rate calculation is the first accurate 3D quantal dynamics study for N + N2 reaction system and the ab initio PES reported here is the first such surface for N3.

Single-determinantal self-consistent-field wavefunctions calculated by the expansion method are reported for the ground state of CO and BF. These calculations were performed at four different internuclear distances, including the experimental equilibrium internuclear distance. Exponents are optimized at all four distances. Potential curves and dipole-moment curves are obtained. From the potential curve, spectroscopic constants are calculated via the Dunham analysis. An SCF calculation was then performed at the calculated Re. Exponents are also optimized. Expectation values of a number of one-electron operators, including the electric dipole moment, the gradient of the electric field at the nucleus, and the Hellmann—Feynman force, are presented and compared with experimental data available. Contour diagrams for the total charge densities and orbital charge densities are included.