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  • 1
    Electronic Resource
    Electronic Resource
    New Heteroaromatic Compounds. XXI.1 Some Tetracyclic Systems2 (1964)
    s.l. : American Chemical Society
    The @journal of organic chemistry 29 (1964), S. 1757-1762 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo01030a023
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of 5H,12H-quinazolino[3,2-a][3,1]benzoxazine-5,12-diones (1976)
    s.l. : American Chemical Society
    The @journal of organic chemistry 41 (1976), S. 2728-2731 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00878a016
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  • 3
    Electronic Resource
    Electronic Resource
    Bent valence excited states of CO2 (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 8382-8388 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The conical intersection regions on the potential energy functions of the valence excited 1,3Σu−, 1,3Δu, 3Σu+, and 1,3Πg states of CO2 have been investigated by ab initio calculations. Using large scale multireference configuration interaction the ordering of the lowest valence excited states of CO2 has been calculated to be 3B2, 3A2, 1A2 followed by 1B2. All these states have bent equilibrium structures and lie energetically below their dissociation asymptotes. The near equilibrium parts of the potential energy functions have been mapped in three dimensions by multiconfiguration self-consistent field calculations. The 1,3B2 and 1,3A2 states differ in their equilibrium angles (118° and 127°, respectively), and have much longer equilibrium distances (around 1.26 A(ring)) than the electronic ground state. Anomalously low values of ca. 800 cm−1 have been calculated for the wave number of the antisymmetric stretching vibrations of the 1A2, 3B2, and 1B2 states. The crossings between the bent valence excited states in the geometry region 90°≤αOCO≤150° and 1.1 A(ring)≤RCO≤1.4 A(ring) have been located.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463408
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  • 4
    Electronic Resource
    Electronic Resource
    A theoretical rotationally resolved infrared spectrum for H2O+ (X 2B1) (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 2818-2833 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Three-dimensional potential energy and electric dipole moment functions for the electronic ground state of H2O+ have been calculated from highly correlated multiconfiguration reference configuration interaction (MRCI) electronic wave functions. The analytic representations of these functions have been used in vibrational and perturbational calculations of the rovibrational absorption spectrum of H2O+. The quartic force fields in normal coordinates have been employed in the evaluation of the equilibrium spectroscopic constants in H2O+, D2O+, and HDO+ by perturbation theory. The equilibrium structure, vibrational band origins, centrifugal distortion constants and rotational energy levels agree very well with the available experimental data. Absolute vibrational band intensities have been calculated from the dipole moment functions and are compared with theoretical integrated band intensities. The radiative lifetimes of excited vibrational states exhibit mode specific variations. The rotationally resolved room temperature absorption spectra have been evaluated ab initio for the pure rotational and the ν2, 2ν2, ν1, ν3, and 3ν2 transitions. The rovibrational electric dipole transition matrix elements and absolute line intensities are given for the most intense transitions. These data take full account of anharmonicity effects and vibration–rotation coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456951
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  • 5
    Electronic Resource
    Electronic Resource
    Ab initio calculations on the four lowest electronic states of AlF+ and AlCl+ (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 5133-5141 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The potential energy curves of the two lowest 2Σ+ (X,B) and the two lowest 2Π (A,C) electronic states of the AlF+ and AlCl+ molecular ions have been calculated using highly correlated multireference configuration interaction (MR-CI) wave functions. It is found that both 2Σ+ states and the C 2Πr state are bound, whereas the A 2Πi state is repulsive. Electronic transition moment functions for all six pairs of states of both ions have also been calculated and used for evaluation of the radiative transition probabilities between bound vibrational states. The calculated charge distributions show that the X and C states are dominated by Coulombic attraction between a doubly charged positive aluminum and the singly charged negative halogen ion. The results provide a new assignment of the photoelectron spectra of the neutral AlF. They are also in good agreement with the recently observed optical B–X emission spectra of both molecular ions and C–X bands of AlCl+. The absence of C–X emission of AlF+ is most likely due to predissociation of the C 2Πr state by the repulsive A 2Πi state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461681
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  • 6
    Electronic Resource
    Electronic Resource
    Calculation of the electronic spectrum for Ar–OH (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 3367-3378 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We calculate the rovibrational structure for the electronic transition of the Ar–OH complex between the ground and first excited electronic states, which correlate asymptotically with Ar(1S0)+OH(X 2Π) and Ar(1S0)+OH(A 2Σ+), respectively. An ab initio potential energy surface is used and the rovibrational states are calculated using a basis set method which couples the electronic spin and orbital angular momentum of the diatomic fragment with the overall rotations and vibrations of the complex. The calculated spectrum is compared with experimental results. In the low-frequency region the spectrum is found to be well ordered and assignment of spectroscopic features in terms of bending and stretching quantum numbers is possible. Close to dissociation, bend–stretch coupling leads to highly mixed states for which such assignments are no longer possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458817
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  • 7
    Electronic Resource
    Electronic Resource
    Ab initio calculations of the vibration–rotation spectrum of HCS− (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 2641-2651 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The three dimensional near equilibrium potential energy and dipole moment surfaces of the electronic ground state of HCS− have been calculated from correlated MCSCF-CI electronic wave functions. These data have been used in perturbation and variational calculations of the bound and electron detachment anharmonic vibration–rotation levels. The electron affinity EA0 is calculated to be 0.41 eV and the equilibrium geometry to be RCH=1.111 A(ring), RCS=1.687 A(ring), α=106°. The fundamental vibrational band origins and integrated absorption band intensities are predicted to be 2648 cm−1/1318 cm−2 atm−1 (CH stretch), 1140 cm−1/145 cm−2 atm−1 (bend), and 911 cm−1/50 cm−2 atm−1 (CS stretch) in HCS−. The components of the dipole moment functions are given analytically. The dipole moment in the vibrational ground state of HCS− has been calculated to be 2.122 D. Radiative transition probabilities among low lying vibrational levels have also been evaluated. It is found that the radiative lifetimes vary in a mode-specific way. The theoretical photoelectron spectrum of HCS− and DCS− is reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454044
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  • 8
    Electronic Resource
    Electronic Resource
    Calculations on vibrational predissociation of Ar–OH (A 2Σ+) (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 8149-8165 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An R-matrix algorithm is developed for executing vibrational predissociation calculations within the Golden Rule approximation. The algorithm is used to calculate vibrational predissociation linewidths and OH product rotational distributions for the quasibound states of Ar–OH (A2 Σ+, v=1). An ab initio potential energy surface obtained with the coupled electron pair approximation is used in the computations. The theoretical results are compared with experiment. The high anisotropy of the system is found to strongly favor vibrational to rotational energy transfer and the product OH (A2 Σ+ , v=0) molecules are produced in highly excited rotational states. Quasibound states associated with excited bending levels are predicted to dissociate more rapidly than those assigned to the ground bend. For metastable states with the same bending quantum number, linewidths are predicted to decrease with increase in the intermolecular stretching quantum number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461295
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  • 9
    Electronic Resource
    Electronic Resource
    Investigation of the spin diffusion in (dicyclopentaheptalene)2SbF6 by pulsed electron spin resonance (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 4543-4547 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have determined the electron spin diffusion constant in (dicyclopentaheptalene)2SbF6 by means of a magnetic field gradient electron spin resonance spin echo technique. Parallel to the chain axis we obtain a value of D(parallel)≈0.064 cm2 s−1. From the comparison of temperature dependent conductivity and susceptibility measurements it is concluded, that the charge carriers are localized in this compound. These localized charge carriers can be described as a system of 1d-Heisenberg spin chains. The measured D(parallel) value therefore corresponds to an effective exchange coupling constant of J≈4.5 meV (J/kB≈51 K).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456792
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  • 10
    Electronic Resource
    Electronic Resource
    Weakly bound NeHF (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 711-721 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have used ab initio methods to characterize the Ne–HF van der Waals complex. The interaction energy was determined using size consistent, correlated CEPA wave functions expanded in a Gaussian basis chosen to represent both intraatomic effects and the low order multipole moments and polarizabilities of Ne and HF. The calculated well depths are −65 cm−1 for linear Ne–HF and −39 cm−1 for linear Ne–FH, with an intervening saddle point at −27 cm−1. The induction contribution to the energy is significantly greater for Ne–HF than for Ne–FH, but dispersion remains the dominant attraction over the region of interest. Converged variational and close-coupling calculations using the ab initio potential surface reveal three bound levels of the Ne–HF stretch mode, and several metastable levels correlating asymptotically with rotationally excited HF( j=1). Though nearly degenerate, the lifetimes of the two metastable Π (body frame Λ=±1) bending levels differ markedly because of different rotational coupling strengths to the Σ (body frame Λ=0) bending state, which undergoes rapid rotational predissociation. From the calculated line positions, widths, and intensities we have synthesized far infrared and infrared spectra of Ne–HF and Ne–DF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457177
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