332 research outputs found
The nature of the excited states of p-nitro-N,N-dimethylaniline.
Contrary to numerous derivatives of p-substituted N,N-dimethyl-aniline, p-nitro-N,N-dimethylaniline, does not form the TICT state. This behaviour is predicted by INDO/S calculations. The calculations also reveal an important role of the Coulomb interaction term in the evolution of intramolecular charge-transfer excited-state energy upon twisting of the dimethylamino group
Highly accurate HF dimer {\it ab initio} potential energy surface
A very accurate, (HF) potential energy surface (PES)is constructed based on \ai\ calculations performed% at the CCSD(T) level of theory with an aug-cc-pVQZ-F12basis set at about 152~000 points.A higher correlation correction is computed at CCSDT(Q) level for 2000 points and is considered alongside other more minorcorrections due to relativity, core-valence correlation and Born-Oppenheimer failure.The analytical surface constructed uses 500 constants to reproduce the \ai\ points with a standard deviation of 0.3 \cm.Vibration-rotation-inversion energy levels of the HF dimer are computed for this PES by variational solution of the nuclear-motionSchr\"{o}dinger using program WAVR4. Calculations over an extended range of rotationally excited states show very good agreementwith the experimental data. In particular the known empirical rotational constants for the ground vibrational states are predicted to better than about 2 MHz. constants for excited vibrational states are reproduced several times more accurately than by previous calculations. %The experimental dissociation energy of the HF dimer is reproduced \ai\ within the experimental accuracy of about 1 \cm\ for the first time. This level of accuracy is shown to extend to higher excited inter-molecular vibrational states and higher excited rotational quantum numbers
A Circular Dichroism Study of Molecular Association of Cinchona Alkaloids and Carboxylic Acids
Circular dichroism (CD) spectra of cinchona alkaloids and their salts with carboxylic acids have been investigated. A eontributionof the exciton type Cotton effect to the 230 nm CD band of free bases in non-polar solvents is suggested to result from the association of alkaloid molecules. Strong association is observed in the case of dihydrocupreidine - an alkaloid with free phenolic group.
Comparison of the CD spectra of salts of alkaloids with
mono- and dicarboxylic acids demonstrates that in the latter case
the p-band Cotton effects originate from the exciton type interactions
between the associated molecules.
The unusual rotations of salts of cinchona alkaloids with
biphenyl 1,1\u27-dicarboxylic acids have been found to originate
from the strong intermolecular exciton coupling, rather than from
the »first-order asymmetric transformation«. The existence of the
two low energy staggered conformations around the C(8)-C(9)
bond in the alkaloid molecule has been confirmed by the MMP2
calculation on a model compound
ExoMol line lists â LI. Molecular line lists for lithium hydroxide (LiOH)
New molecular line lists for lithium hydroxide (6Li16O1H and 7Li16O1H isotopologues) covering wavelengths λ > 1 Ό
m (0â10â000 cmâ1 range) are presented. Each line list contains around 300 million transitions between rotationâvibration energy levels with total angular momentum up to J = 95, applicable for temperatures up to T â 3500 K. Line list calculations were based on a previously published, high-level ab initio potential energy surface and a newly computed dipole moment surface of the ground X~1ÎŁ+
electronic state. Lithium-containing molecules are important in a variety of stellar objects and there is potential for LiOH to be observed in the atmospheres of exoplanets. Transit spectra are simulated using the rocky super-Earth 55 Cancri e as an example with two different atmospheric scenarios including LiOH. This work provides the first, comprehensive line lists of LiOH to facilitate its future molecular detection. The OYT7 line lists along with the associated temperature- and pressure-dependent molecular opacities can be downloaded from the ExoMol database at www.exomol.com and the CDS astronomical database
ExoMol line lists -- LI. Molecular line list for lithium hydroxide (LiOH)
A new molecular line list for lithium hydroxide (LiOH)
covering wavelengths m (the 0-10000 cm range) is
presented. The OYT7 line list contains over 331 million transitions between
rotation-vibration energy levels with total angular momentum up to and
is applicable for temperatures up to K. Line list calculations
are based on a previously published, high-level \textit{ab initio} potential
energy surface and a newly computed dipole moment surface of the ground
\tilde{X}\,^1\Sigma^+ electronic state. Lithium-containing molecules are
important in a variety of stellar objects and there is potential for LiOH to be
observed in the atmospheres of exoplanets. This work provides the first,
comprehensive line list of LiOH and will facilitate its future molecular
detection. The OYT7 line list along with the associated temperature- and
pressure-dependent opacities can be downloaded from the ExoMol database at
www.exomol.com and the CDS astronomical database
Experimental Confirmation of Quantum Monodromy: The Millimeter Wave Spectrum of Cyanogen Isothiocyanate NCNCS
We have made energy-momentum maps for the experimental end-over-end rotational energy and the two-dimensional bending vibrational energy, both of which confirm the dominating effects of nontrivial quantum monodromy in cyanogen isothiocyanate. Accidental resonances in the rotational spectra yield accurate intervals between bending states
Systematic calculation of molecular vibrational spectra through a complete Morse expansion
We propose an accurate and efficient method to compute vibrational spectra of
molecules, based on exact diagonalization of an algebraically calculated matrix
based on powers of Morse coordinate. The present work focuses on the 1D
potential of diatomic molecules: as typical examples, we apply this method to
the standard Lennard-Jones oscillator, and to the ab initio potential of the H2
molecule. Global cm-1 accuracy is exhibited through the H2 spectrum, obtained
through the diagonalization of a 30 x 30 matrix. This theory is at the root of
a new method to obtain globally accurate vibrational spectral data in the
context of the multi-dimensional potential of polyatomic molecules, at an
affordable computational cost.Comment: 30 pages including 6 figure
Splitting the pie: rent distribution in alliances and networks
This paper addresses the issue of how relational rents, generated through alliances, are distributed to the participating firms. We argue that rent distribution is influenced by factors affecting both jointly generated common benefits and private benefits gained from the alliance relationship. We draw on four perspectives to explain these various effects. The first three, namely the resource dependence perspective, related resources perspective, and structural holes perspective, essentially highlight the private âexploitationâ opportunities that a firm's alliance network presents the focal firm. In contrast, the resource development perspective underscores the private âexplorationâ benefits a firm potentially derives from its alliance network. Copyright © 2008 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58065/1/1391_ftp.pd
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