Ab initio potential energy surfaces, total absorption cross sections, and product quantum state distributions for the low-lying electronic states of N 2 O Resonance Raman spectra measured for ClNO photoexcited at 212.5, 219, and 222 nm produce evidence that the strong transition at the vacuum ultraviolet end of the merged A band system dominates to wavelengths as long as 222 nm. The spectral resolution is sufficient to enable definitive assignments of excited vibrational levels in the ground electronic state, several of which have not been previously observed. A curvilinear coordinate model of the ground state potential surface around the Franck-Condon region has been constructed. This model yields vibrational eigenvalues in excellent agreement with all known transitions.

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Orthogonal compact-support Daubechies wavelets are employed as bases for both space and time variables in the solution of the time-dependent Schrodinger equation. Initial value conditions are enforced using special early-time wavelets analogous to edge wavelets used in boundary-value problems. It is shown that the quantum equations may be solved directly and accurately in the discrete wavelet representation, an important finding for the eventual goal of highly adaptive multiresolution Schrodinger equation solvers. While the temporal part of the basis is not sharp in either time or frequency, the Chebyshev method used for pure time-domain propagations is adapted to use in the mixed domain and is able to take advantage of Hamiltonian matrix sparseness. The orthogonal separation into different time scales is determined theoretically to persist throughout the evolution and is demonstrated numerically in a partially adaptive treatment of scattering from an asymmetric Eckart barrier.

It is well known that the chemical reactivity of small gallium–arsenide clusters can be sensitive to cluster size and geometrical structure. We have performed ab initio calculations probing the interaction of NH3 with different sites of a free Ga5As5 cluster. Our results show that bonding tends to be strongest at gallium sites. Adsorption of NH3 is found to induce strong relaxation of the cluster global geometry. The cluster sites are compared with sites on the (111) bulk surface of gallium arsenide, and the possibility for exploring the similarity between cluster reactivity and surface reactivity is discussed.

A densityfunctional study of cluster reactivity. III. NH3 on a free Ga5As+ 5 cationic cluster A densityfunctional study of cluster reactivity: Ammonia reacting with a free Ga5As5 clusterWe present an investigation of the interaction of two ammonia molecules with the Ga 5 As 5 cluster. The ͑NH 3 ) 2 Ga 5 As 5 complex is found to be stable, in agreement with experiments. We find a significant decrease in the binding energy for the second ammonia, compared to single ammonia adsorption in agreement with experimental results. We investigate the site dependence of the ammonia-ammonia interaction and demonstrate that the adsorption of a single ammonia on certain sites prevents further adsorption of ammonia on certain other sites.