Vibronic effect

A good example is the spectnun of naphthalene. The two lowest excited states have 62 and synnnetries and are allowed for one-photon transitions. A weak transition to one of these is observable in die two-photon spectnun [33], presumably made allowed by vibronic effects. Much stronger two-photon transitions are observable at somewhat higher energies to a and an A state lying quite close to the energies predicted by theory many years earlier [34]. 

Bailey C G, Dessent C E FI, Johnson M A and Bowen K FI 1996 Vibronic effects in the photon energy-dependent photoelectron spectra of the CFIjCN dipole-bound anion J. Chem. Phys. 104 6976-83... 

V 0.48), Ammeter and Swalen also calculated the adiabatic distortion parameter for the Co(Cp)2/Fe(Cp)2 system, finding A = 528 cm 1. In both cases however calculations were carried out to determine the value of the purely static distortion which would reproduce, via the vibronic coupling mechanism, the results for c and 45- For the Ru(Cp)2 host the corrected value of A proved to be 200 cm 1 and for the Fe(Cp)2 host 840 cm-1. Thus in the Ru(Cp)2 host, with a rather long metal to carbon distance, the vibronic effect... 

Quantum Systems in Chemistry and Physics is a broad area of science in which scientists of different extractions and aims jointly place special emphasis on quantum theory. Several topics were presented in the sessions of the symposia, namely 1 Density matrices and density functionals 2 Electron correlation effects (many-body methods and configuration interactions) 3 Relativistic formulations 4 Valence theory (chemical bonds and bond breaking) 5 Nuclear motion (vibronic effects and flexible molecules) 6 Response theory (properties and spectra atoms and molecules in strong electric and magnetic fields) 7 Condensed matter (crystals, clusters, surfaces and interfaces) 8 Reactive collisions and chemical reactions, and 9 Computational chemistry and physics. 

The intensities of polarized ligand field spectra ns-n ) of V(ethyl-dtp)3 doped into the corresponding indium(III) compoimd exhibit a relatively small temperature dependence. The source of the large intensities of the d-d transition is the static distortion of the ligand field n ) and not vibronic effects to any appreciable extent. 

Nuclear Motion, Vibronic Effects and Flexible Molecules... 

Nuclear motion, vibronic effects, and flexible molecules (Chair J. Maruani) Response theory—Properties and spectra Atoms and molecules in strong electric and magnetic fields (Chair J. Gerratt)... 

Nuclear motion vibronic effects, flexible molecules ,... 

The results of these calculations follow a similar pattern to the earlier studies of the absorption spectra (146). In the case of the Q bands, the more sophisticated MCD calculation utilizing TDDFT is only a refinement of the four-orbital model. A single A term is predicted with small overall MCD intensity but significant Aj/Dj ratio. This provides further evidence that the more complicated series of bands observed in the Q band of the absorption and MCD spectra is due to vibronic effects. In the cases of NiTPP and... 

Beside these statical mixings just considered, the vibronic effects must be analyzed. Van Vleck (25) has shown that the vibronically induced noncentrosymmetric field Khem is related to the centrosymmetric static field hol by the approximate formula... 

Beveridge and Miller B1> in an INDO study, have calculated the vibronic effects in substituted methyl redicals and have satisfactorily reproduced the trends of isotope effects on isotropic coupling constants (Table 37). 

The Spin Hamiltonian Effective Approach to the Vibronic Effects - Selected Cases... 

The foregoing discussion implies that in order to understand the doping behaviour observed in the optical spectra of the fullerides, we must consider both bonding and vibronic effects. A simple method of separating these two contributions has been given in Ref. [7] and is outlined here for the sake of completeness. The shift in mode frequency is expressed as sum of two contributions ... 

We discuss here two examples of vibronic effects in polynuclear highly symmetrical transition metal clusters. The existence of degenerate and quasi-degenerate molecular orbitals in their energy spectra results in the Jahn-Teller effect or in the vibronic mixing of different electronic states. We show that both quantum-chemical methods and model approaches can provide valuable information about these vibronic effects. In the case of the hexanuclear rhenium tri-anion, the Jahn-Teller effect is responsible for the experimentally observed tetragonal distortion of the cluster. The vibronic model of mixed-valence compounds allows to explain the nature of a transient in the photo-catalytic reaction of the decatungstate cluster. 

Concluding this paragraph we can note that DFT methods can give important qualitative and quantitative results for vibronic effects in polynuclear clusters. However, as for mononuclear complexes the DFT methods can be used with a special care for Jahn-Teller systems. 

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