Search results for "Electronic states"
showing 10 items of 24 documents
Theoretical Investigation of the Low-Energy States of CpMoCl(PMe 3 ) 2 and Their Role in the Spin-Forbidden Addition of N 2 and CO
2003
International audience; A recent computational investigation of Jahn−Teller effects in unsaturated 16-electron d4d6 [CpMLn] complexes (Abu-Hasanayn, F.; Cheong, P.; Oliff, M. Angew. Chem.2002, 41, 2120) highlighted the typical presence of two spin-triplet and two singlet states of competing stability in these complexes and pointed out the necessity to account for more than one electronic state in studies thereof. Consequently, we have reinvestigated the addition of N2 to all the four low-energy states of CpMoCl(PH3)2, a reaction for which previously only one singlet and one triplet state have been considered (Keogh, D. W.; Poli, R. J. Am. Chem. Soc.1997, 119, 2516). The present study was pe…
A Theoretical Determination of the Low-lying Electronic States of the p-Benzosemiquinone Radical Anion
2000
The low-lying electronic states of the p-benzosemiquinone radical anion are studied using multiconfigurational second-order perturbation theory (CASPT2) and extended atomic natural orbital (ANO) ba...
Direct to Indirect Crossover in III-VI Layered Compounds and Alloys under Pressure
1999
The pressure dependence of the optical absorption edge of In1± xGaxSe (0 < x < 0.2) and GaTe has been investigated in order to determine the direct to indirect crossover pressure and the energy difference between the absolute and subsidiary minima of the conduction band at ambient pressure. In the In1± xGaxSe alloy, the crossover pressure decreases with increasing Ga proportion. For InSe, from the extrapolation to x = 0 the band crossover is found to occur at 4.3 GPa and the subsidiary minimum of the conduction band is located, at ambient pressure, (0.32 0.02) eV above the absolute minimum. In addition, the energy difference between the conduction band minima is shown to decrease linearly w…
Electrically Conductive Phthalocyanine Assemblies. Structural and Non-Integer Oxidation Number Considerations
1990
Aggregation is a well-known phenomenon in phthalocyanine chemistry. Interactions can occur between adjacent phthalocyanine rings, both in organic and aqueous phases, resulting in coupling between the electronic states of two, or more, phthalocyanine units [1].
Mechanism of photoluminescence in intrinsically disordered CaZrO3 crystals: First principles modeling of the excited electronic states
2017
Abstract CaZrO3 (CZO) powders obtained by the polymeric precursor method at 400 °C, and then, the samples were annealed at different temperatures (400, 600, 800, and 1000 °C) and characterized by X-ray diffraction, Raman and ultraviolet–visible spectroscopic methods, along with photoluminescence (PL) emissions. First principle calculations based on the density functional theory (DFT), using a periodic cell models, provide a theoretical framework for understanding the PL spectra based on the localization and characterization of the ground and electronic excited states. Fundamental (singlet, s ) and excited (singlet, s* , and triplet, t* ) electronic states were localized and characterized us…
Interaction-induced spin polarization in quantum dots.
2010
The electronic states of lateral many electron quantum dots in high magnetic fields are analyzed in terms of energy and spin. In a regime with two Landau levels in the dot, several Coulomb blockade peaks are measured. A zig-zag pattern is found as it is known from the Fock-Darwin spectrum. However, only data from Landau level 0 show the typical spin-induced bimodality, whereas features from Landau level 1 cannot be explained with the Fock-Darwin picture. Instead, by including the interaction effects within spin-density-functional theory a good agreement between experiment and theory is obtained. The absence of bimodality on Landau level 1 is found to be due to strong spin polarization.
The effects of the intense laser field on donor impurities in a cylindrical quantum dot under the electric field
2011
Abstract For different nitrogen and indium concentrations, intense laser field (ILF) effect on donor impurity binding energy in a cylindrical Ga x In 1 − x N y As 1 − y / GaAs quantum dot (QD) has been studied. Results show that ILF creates an additional confinement on the electronic and impurity states in QD and increases nitrogen and indium concentration effects on electronic states.
The multi-state CASPT2 method
1998
Abstract An extension of the multiconfigurational second-order perturbation approach CASPT2 is suggested, where several electronic states are coupled at second order via an effective-Hamiltonian approach. The method has been implemented into the MOLCAS-4 program system, where it will replace the single-state CASPT2 program. The accuracy of the method is illustrated through calculations of the ionic-neutral avoided crossing in the potential curves for LiF and of the valence-Rydberg mixing in the V-state of the ethylene molecule.
Nonadiabatic orientation, toroidal current, and induced magnetic field in BeO molecules.
2008
It is predicted that oriented BeO molecules would give rise to unprecedentedly strong, unidirectional electric ring current and an associated magnetic field upon excitation by a right or left circularly polarized laser pulse into the first excited degenerate singlet state. The strong toroidal electric ring current of this state is dominated by the ring current of the 1π± orbital about the molecular axis. Our predictions are based on the analysis of the orbital composition of the states involved and are substantiated by high level electronic structure calculations and wavepacket simulations of the laser-driven orientation and excitation dynamics. Luis.Serrano@uv.es
A theoretical study of the lowest electronic states of azobenzene: the role of torsion coordinate in the cis-trans photoisomerization
2003
In the present paper we report the results of a multiconigurational computational study on potential- energy curves of azobenzene along the NN twisting to clarify the role of this coordinate in the decay of the S2(pp*) and S1(np*) states. We have found that there is a singlet state, S3 at the trans geometry, on the basis of the doubly excited coniguration n 2 p* 2 , that has a deep minimum at about 90 of twisting, where it is the lowest excited singlet state. The existence of this state provides an explanation for the short lifetime of S2(pp*) and for the wavelength-dependence of azobenzene photochem- istry. We have characterized the S1(np*) state by calcu- lating its vibrational frequencie…