Rotationally resolved resonance enhanced multiphoton ionisation spectra of the B̃(1)E'' state of NH2D are presented and analysed. The analysis indicates a small (34.9 cm(-1)) lifting of the vibronic degeneracy of the zero point level, approximately equal in sign but opposite in magnitude to the splitting observed in NHD2 in previous work. This observation is consistent with previous measurements...

We report a general method for the calculation of Jahn-Teller coupling constants by ab initio methods widely available today in standard packages. The vibrational frequencies corresponding to those obtained experimentally are calculated at the symmetric position using a generalized restricted Hartree-Fock (GRHF) wavefunction. The energy of the symmetric configuration is calculated as a conical ...

We investigated the symmetry breaking mechanism in cubic octa-tert-butyl silsesquioxane and octachloro silsesquioxane monocations (Si8O12(C(CH3)3)8(+) and Si8O12Cl8(+)) using density functional theory (DFT) and group theory. Under Oh symmetry, these ions possess (2)T2g and (2)Eg electronic states and undergo different symmetry breaking mechanisms. The ground states of Si8O12(C(CH3)3)8(+) and Si...

The Jahn-Teller effect in the first two excited states of the nitrate radical NO3 has yet to be experimentally elucidated. In this paper, direct evidence of strong Jahn-Teller interactions in the A state is presented from the first complete absorption spectrum of the A2E'' <-- X2A(2)' transition of NO3 in the gas phase in the region 5900-9000 cm(-1), at moderate resolution (0.15 cm(-1)). The ob...

Laser-induced fluorescence (LIF) and laser-excited dispersed fluorescence (LEDF) spectra of the cycloheptatrienyl (tropyl) radical C7H7 have been observed under supersonic jet-cooling conditions. Assignment of the LIF excitation spectrum yields detailed information about the A-state vibronic structure. The LEDF emission was collected by pumping different vibronic bands of the A 2E"3<--X 2E"2 el...

For a rigorous quantum simulation of nonadiabatic dynamics of electrons and nuclei, knowledge of not only the first-order but also the second-order nonadiabatic couplings (NACs) is required. Here, we propose a method to efficiently calculate the second-order NAC from time-dependent density functional theory (TDDFT), on the basis of the Casida ansatz adapted for the computation of first-order NA...

27 I lanson, P. I , . , Otto, I I . , Barton, N. and Jahn, K. (1995) J. I3iol. Chcm. 270, 16955-16961 28 Ilayashi, ‘I.., Yamasaki, S., Naucnburg, S., I l k , ‘1’. and Niemann, 11. (1995) EMRO J. 14, 2317-2325 20 Kec, Y., Idin, R. C., Ilsu, S.-C. and Schellcr, K. 11. ( 1995) Neuron 14, 991 -998 30 Chapman, E:. K., An, S., Barton, N. and Jahn, R. (1994) J . I3iol. Chem. 269, 27427-27432 3 I Koth,...

We discuss Mott insulating and metallic phases of a model with eg orbital degeneracy to understand physics of Mn perovskite compounds. Quantum Monte Carlo and Lanczos diagonalization results are discussed in this model. To reproduce experimental results on charge gap and Jahn-Teller distortions, we show that a synergy between the strong correlation effects and the Jahn-Teller coupling is import...

Starting from a spin-orbital model for doped manganites, we investigate a competition between ferromagnetic and antiferromagnetic order in a one-dimensional model at finite temperature. The magnetic and orbital order at half filling support each other and depend on a small antiferromagnetic superexchange between t2g spins and on an alternating Jahn-Teller potential. The crossover to a metallic ...

The ground state of acceptors in cubic semiconductors is fourfold degenerate (I?,) and the interaction with the lattice vibrations leads to the possibility of a Jahn-Teller effect [l]. The extended nature of the wave function of these defects [ 2 ] has two important consequences : (i) the interaction is mainly with long-wavelength acoustic phonons, (ii) because of the large elastic energy assoc...