152 research outputs found

    Scattering and bound-state solutions to the wave equation for one electron in the presence of a physical dipole

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    This paper presents a quantum-mechanical analysis of the interaction of one electron with a physical dipole (two physically separated charges). Aspects of threshold laws in the continuous spectrum are treated. In addition there are determinations of energies of some dipole bound states. The bound-state calculations are used as a model for certain high dipole moment molecules, where, together with empirical data, an equivalent dipole length may be determined. These model calculations predict that the bound dipole orbital in high dipole molecule ions should have a node between its valence part and the more remote part where the majority of the charge resides. Some results from the two parts of the treatment are brought together to calculate the asymmetry factor of the photoelectron signal for uracil, measured by Schiedt et al

    Electron tunneling, charge transfer, and the intermolecular forces between two H\u3csub\u3e2\u3c/sub\u3e molecules

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    The spherically averaged van der Waals potential for the system H2–H2 has been calculated using a nonorthogonal CI method based on SCF orbitals for the individual molecules. With suitable restrictions on the CI calculation we have isolated various contributions to the van der Waals potential, and have found that charge transfer and dispersion effects are comparable to distances corresponding to the potential minimum. The charge transfer contribution is further discussed in terms of a mechanism involving electron tunneling through the intervening space between the molecules. Our calculation gives a spherically averaged van der Waals well depth of 2.96 meV at 3.49 Å. Experimental values are 3.00 meV at 3.49 Å. The Journal of Chemical Physics is copyrighted by The American Institute of Physics

    The structures of \u3ci\u3ec\u3c/i\u3e-C\u3csub\u3e4\u3c/sub\u3eF\u3csub\u3e8\u3c/sub\u3e and \u3ci\u3ec\u3c/i\u3e-C\u3csub\u3e4\u3c/sub\u3eF\u3csub\u3e8\u3c/sub\u3e\u3csup\u3e¯\u3c/sup\u3e and the adiabatic electron affinity of \u3ci\u3ec\u3c/i\u3e-C\u3csub\u3e4\u3c/sub\u3eF\u3csub\u3e8\u3c/sub\u3e

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    Calculations at the 6311G(dps) level have been used to elucidate the structures of octafluorocyclobutane c-C4F8 and its negative ion c-C4F8¯. With no empirical adjustments, we obtain 0.640 eV for the adiabatic electron affi nity of c-C4F8. This may be compared with an experimental value of 0.63 ± 0.05 eV from the FALP method. c-C4F8 has unusual features in that there is an increase in symmetry, D2d to D4h, in going from the neutral molecule to the negative ion, and the singly occupied molecular orbital in the ion has an unexpected nodal structure

    Complex energy shift and background phase shift for simulated electron-molecular shape resonances

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    Feshbach-Fano resonance theory (FFRT) is used to determine the energy dependence of the complex energy shift function, consisting of the real energy shift and the resonance width, and the background phase shift for several simulated molecular shape resonances. Attention is paid to the way the choice of the quasibound state (QBS) function required in the FFRT affects these energy dependencies. An overlap criterion for choosing an optimal QBS function is proposed. Using our treatment on t-butylchloride, carbon tetrachloride, ethylene, and benzene, we give numerical results for specific cases of l = 1 through 4. We find that the real energy shift function does not vary greatly over the width of the resonance, although the magnitude of the shift can be fairly large. We also find that the behavior of the background phase shift due to orthogonality scattering is sensitive to the presence of long-range potentials

    Projected Hartree product wavefunctions. VI. Natural orbital CI expansions in nonsinglet cases

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    The NSO\u27s and NO\u27s have been determined for some wavefunctions for Li, Be1+, B2+, C3+ 2S, and Be 3S wavefunctions containing radial correlation. It is shown how the NO\u27s may be utilized to form rapidly converging CI expansions in general. The role of the NSO\u27s in this problem is discussed. ©1973 The American Institute of Physic

    Representation of \u3ci\u3eab initio\u3c/i\u3e energy surfaces by analytic functions

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    A method for the analytical representation of ab initio energy surface results is described. For a three-atom surface, the potential function is written as a sum of atomic, two-body, and three-body terms. This allows an easy fitting of the whole surface, including the dissociated and united atom limits. The theory is applied to an H3 surface of limited accuracy calculated for these purposes. Comparisons are made, where possible, with more accurate calculations. Extensions to surfaces involving four or more atoms are also discussed

    Representation of \u3ci\u3eab initio\u3c/i\u3e energy surfaces by analytic functions

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    A method for the analytical representation of ab initio energy surface results is described. For a three-atom surface, the potential function is written as a sum of atomic, two-body, and three-body terms. This allows an easy fitting of the whole surface, including the dissociated and united atom limits. The theory is applied to an H3 surface of limited accuracy calculated for these purposes. Comparisons are made, where possible, with more accurate calculations. Extensions to surfaces involving four or more atoms are also discussed

    Mental State Attribution and Body Configuration in Women

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    Body configuration is a sexually dimorphic trait. In humans, men tend to have high shoulder-to-hip ratios. Women in contrast, often have low waist-to-hip ratios (WHR); i.e., narrow waists and broad hips that approximate an hour-glass configuration. Women with low WHR’s are rated as more attractive, healthier, and more fertile. They also tend to have more attractive voices, lose their virginity sooner, and have more sex partners. WHR has also been linked with general cognitive performance. In the present study we expand upon previous research examining the role of WHR in cognition. We hypothesized that more feminine body types, as indexed by a low WHR, would be associated with cognitive measures of the female “brain type,” such as mental state attribution and empathy because both may depend upon the activational effects of estrogens at puberty. We found that women with low WHRs excel at identifying emotional states of other people and show a cognitive style that favors empathizing over systemizing. We suggest this relationship may be a byproduct of greater gluteofemoral fat stores which are high in the essential fatty acids needed to support brain development and cellular functioning. It is interesting to note that our findings suggest lower WHR females, who are more likely to be targeted for dishonest courtship, may be better at identifying disingenuous claims of commitment

    Hydrogen Bond Energies in Carboxylic Acids

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    A question of interest to the study of the chemisorption of carbon monoxide on iron is whether the carbon is desorbed with the same oxygen to which it was bonded prior to the adsorption. A mixture of C13O and CO18 in the desorbed gas in amounts greater than expected from normal abundance ratios shows that an intermolecular oxygen exchange occurs

    Spin-Exchange-Induced Circularly Polarized Molecular Fluorescence

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    We have measured the circular polarization of light emitted from both atomic H and molecular H2 after bombarding H2 with longitudinally polarized electrons. For both atomic and molecular fluorescence near threshold we observe a circular polarization as great as 10% of the electron polarization. This represents the first direct observation of spin transfer in electron-molecule collisions
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