Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Vibrational configuration interaction

Tucker, S. C., Thompson, T. C., Lauderdale, J. G., and Truhlar, D. G. (1988), A Vibrational Configuration Interaction Program for Energies and Resonance Widths, Comp. [Pg.235]

Fujisaki, H. Yagi, K. Hirao, K. Straub, J. E., Quantum dynamics of V-methylacetamide studied by the vibrational configuration interaction method. Chem. Phys. Lett. 2007, 443,6-11. [Pg.227]

Hirata et al. used the vibrational self-consistent field (VSCF), vibrational configuration-interaction (VCI), and vibrational second-order Moller-Plesset perturbation (VMP2) methods. The VSCF expressed the vibrational wave functions as products of 52 harmonic oscillator (HO) wave functions. The VCI wave function was a linear combination of the 2000 lowest-energy VSCF model products. The obtained vibrational corrections to V(F, H) and V(F, F) were 18.4Hz and — 42.9 Hz, respectively. The vibrational correction... [Pg.178]

Begue D, Gohaud N, Pouchan C, Cassam-Chenai P, lievin J (2007) A comparison of two methods for selecting vibrational configuration interaction spaces on a heptatomic system Ethylene oxide. J Chem Phys 127 164115... [Pg.23]

Christiansen has reviewed the reeently developed theoretieal methods for the calculation of vibrational energies and wavefunetions. The main focus is on wavefunction methods using the vibrational self-eonsistent field (VSCF) method as starting point, and ineludes vibrational eonliguration interaction (VCI), vibrational Moller-Plesset (VMP), and vibrational coupled cluster (VCC) approaches. The eonvergenee of these different sets of methods towards the full vibrational configuration interaction (FVCI) result has been discussed as well as the application of this formalism to determine vibrational contributions to response properties. [Pg.29]

Circular Dichroism Vibrational Configuration Interaction Configuration Interaction PCI-X and Applications Density Functional Theory (DFT), Hartree-Fock (HF), and the Self-consistent Field Magnetic Circular Dichroism of n Systems Molecular Magnetic Properties Nucleic Acid Conformation and Flexibility Modeling Using Molecular Mechanics Spectroscopy Computational Methods Stereochemistry Representation and Manipulation. [Pg.380]

Scott, A. P., Radom, L., 1996, Harmonic Vibrational Frequencies An Evaluation of Hartree-Fock, Moller-Plesset, Quadratic Configuration Interaction, Density Functional Theory, and Semiempirical Scale Factors , J. Phys. Chem., 100, 16502. [Pg.300]

Starting from the normal mode approximation, one can introduce anharmonicity in different ways. Anharmonic perturbation theory [206] and local mode models [204] may be useful in some cases, where anharmonic effects are small or mostly diagonal. Vibrational self-consistent-field and configuration-interaction treatments [207, 208] can also be powerful and offer a hierarchy of approximation levels. Even more rigorous multidimensional treatments include variational calculations [209], diffusion quantum Monte Carlo, and time-dependent Hartree approaches [210]. [Pg.24]

Scott AP, Radom L(1996) Harmonic vibrational frequencies An evaluation of Hartree-Fock, Moller-Plesset, quadratic configuration interaction, density functional theory, and semiempirical scale factors. J Phys Chem 100 16502-16513... [Pg.101]

Five isotopomers of Sia were studied in Ref (20), and are labeled as follows Si- Si- Si (I) Si- Si- Si (II) Si- Si- Si (III) Si- "Si- Si (IV) Si- Si- °Si (V). Rotational constants for each (both corrected and uncorrected for vibration-rotation interaction) can be found towards the bottom of Table I. Structures obtained by various refinement procedures are collected in Table II. Two distinct fitting procedures were used. In the first, the structures were refined against all three rotational constants A, B and C while only A and C were used in the second procedure. Since truly planar nuclear configurations have only two independent moments of inertia (A = / - 4 - 7. = 0), use of B (or C) involves a redundancy if the other is included. In practice, however, vibration-rotation effects spoil the exact proportionality between rotational constants and reciprocal moments of inertia and values of A calculated from effective moments of inertia determined from the Aq, Bq and Co constants do not vanish. Hence refining effective (ro) structures against all three is not without merit. Ao is called the inertial defect and amounts to ca. 0.4 amu for all five isotopomers. After correcting by the calculated vibration-rotation interactions, the inertial defect is reduced by an order of magnitude in all cases. [Pg.196]

The vibration-rotation interaction term makes the Hamiltonian for nuclear motion of a polyatomic molecule difficult to deal with. Frequently, this term is small compared to the other terms. We shall make the initial approximation of omitting Tvib rot. The rotational kinetic energy TTOt involves the moments of inertia of the molecule, which in turn depend on the instantaneous nuclear configuration. However, the vibrational motions are much faster than the rotational motions, so that we can make the approximation of calculating the moments of inertia averaged over the vibrational motions. [Pg.103]

The wavefunction developed in the preceding subsection is, of course, only a first approximation to the true molecular continuum wavefunction. We have thus far considered only the nonvibrating molecule, and treated the resulting Born-Oppenheimer states as if they were the true eigenstates. In a real system vibrational motion of the nuclei, configuration interaction between vibronic states, etc., must be included in the description. [Pg.291]


See other pages where Vibrational configuration interaction is mentioned: [Pg.207]    [Pg.208]    [Pg.208]    [Pg.345]    [Pg.47]    [Pg.28]    [Pg.29]    [Pg.87]    [Pg.324]    [Pg.422]    [Pg.207]    [Pg.208]    [Pg.208]    [Pg.345]    [Pg.47]    [Pg.28]    [Pg.29]    [Pg.87]    [Pg.324]    [Pg.422]    [Pg.365]    [Pg.121]    [Pg.322]    [Pg.689]    [Pg.373]    [Pg.43]    [Pg.285]    [Pg.302]    [Pg.61]    [Pg.158]    [Pg.68]    [Pg.950]    [Pg.68]    [Pg.117]    [Pg.298]    [Pg.389]    [Pg.322]    [Pg.158]   


SEARCH



Anharmonicity vibrational configuration interaction

Configuration Interaction

Configurational interaction

Vibrational configuration interaction (VCI

Zero-point energy vibrational configuration interaction

© 2024 chempedia.info