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The geometric structure and bonding properties of medium-sized ArnH+ clusters (n = 2-35), in which a proton is wrapped up in a number of Ar atoms, are investigated by applying a diatomics-in-molecules (DIM) model with ab-initio input data generated by means of multi-reference configuration-interaction (MRCI) computations. For the smaller complexes, n = 2-7, cross-checking calculations employing the coupled-cluster approach (CCSD) with the same one-electron atomic basis set as for the input data calculations (aug-cc-pVTZ from Dunning), show good agreement thus justifying the extension of the DIM study to larger n. Local minima of the multi-dimensional potential-energy surfaces (PES) are determined by combining a Monte-Carlo sampling followed, for each generated point, by a steepest-descent optimization procedure. For the electronic ground state of the ArnH+ clusters, the global minimum (corresponding to the most stable structure of the cluster) as well as secondary minima are found and analyzed. The structural and energetic data obtained reveal the building-up regularities for the most stable structures and make it possible to formulate a simple increment scheme. The low-lying excited states are also calculated by the DIM approach; they all turn out to be globally repulsive
The electronic and geometric structure, stability and molecular properties of the cationic van-der-Waals complex Ar2H+ in its ground electronic state are studied by means of two ab-initio quantum-chemical approaches: conventional configuration interaction (multi-reference and coupled cluster methods) and a diatomics-in-molecules model with ab-initio input data.
Motivated by the possible importance of OBrO in atmospheric photochemistry, multireference configuration interaction calculations of the low-lying excited states were carried out to obtain information about the electronic vertical spectrum up to excitation energies of about 6 eV from the ground state, including the transition dipole moments, and about possible photodissociation pathways, based on one-dimensional cuts through the potential energy surfaces for dissociation into BrO + O and Br + O2, respectively. In addition, for probing the angle dependence the bending potentials were also calculated.
Complete 3D potential energy surfaces for the two lowest electronic states of the system (N2H)+
(1996)
Ab-initio study of the potential energy surfaces of doublet valence and Rydberg states of FCO
(1994)
Ab-initio investigation of the vibrational structure of absorption and emission spectra of FCO
(1994)
A weak-mode representation of floppy molecules. IV. Spectroscopic states of model HCN and CNH
(1997)
Quasiclassical dynamics of proton scattering by N2 on an improved ab initio potential energy surface
(2001)
An improved analytical representation of the ground electronic potential energy surface (PES) of the (H+, N2) system is generated using the ab initio data reported in our earlier work. The new analytical PES function describes adequately the global behavior and in particular the angular dependence of the interaction as well as the long-range part so that it is amenable to scattering studies. We investigate the elastic and inelastic H+-N2 scattering dynamics on this PES by the quasiclassical trajectory method for center-of-mass collision energies in the range 29-144 eV. The trajectory results thus obtained are compared with the available experimental findings and with recent quantum-mechanical (vibrational close-coupling rotational infinite-order sudden) results. Despite some differences, the experimental data are well reproduced by the present calculations.