Metastable He*(21S,23S) atomic beams at thermal energies have been used more frequently as soft surface probes recently. Due to the He*J< surface (M) interactions there is a certain probability I' of He being deexcited in front of the surface. The deexcitation energies (E* = 20.6 and 19.8 eV respectively for He * 1 -2 S and -23S) that are released are sufficient to ionize electrons of surfaces....

The task of finding saddle points on potential energy surfaces plays a crucial role in understanding the dynamics of a micromolecule as well as in studying the folding pathways of macromolecules like proteins. The problem of finding the saddle points on a high dimensional potential energy surface is transformed into the problem of finding decomposition points of its corresponding nonlinear dyna...

We report a detailed dynamics and kinetics study of the title reaction over the range of translational energies 0.418 e Etr/kJ mol-1 e 62.760 by employing the quasiclassical trajectory method and a recently reported double many-body expansion potential energy surface for ground-state HO3. A comparison of the calculated thermal rate constants with the available experimental results is also prese...

A study of the intermolecular potential-energy surface ~IPS! and the intermolecular states of the perprotonated and perdeuterated benzene–He complex is reported. From a fit to ab initio data computed within the coupled cluster singles and doubles including connected triples model for 280 interaction geometries, an analytic IPS including twoto four-body atom–atom terms is obtained. This IPS, and...

Quartic force fields for the ground electronic states of the most stable C4 radical isomers [l-C4(X 3 g ) and r-C4(X Ag)] are computed at the same level of theory. These computations are performed using interaction configuration ab initiomethods and the cc-pVTZ basis set. These force fields on symmetry-adapted coordinates are derived from full six-dimensional potential energy surfaces generated...

We present some new theoretical and computational results for the stationary points of bulk systems. First we demonstrate how the potential energy surface can be partitioned into catchment basins associated with every stationary point using a combination of Newton-Raphson and eigenvector-following techniques. Numerical results are presented for a 256-atom supercell representation of a binary Le...

A femtosecond negative ion-neutral-positive ion charge reversal apparatus has been developed, following the concept of Wöste and Berry, to carry out spectroscopy of transient neutral species along the reaction coordinate. We report studies of the ultrafast dynamics of linear Ag3 produced by photodetachment of linear Ag3. The background-free time-resolved multiphoton ionization spectra of Ag3 ta...

Multidimensional Kramers rate theory is employed to examine the influence exerted by double bonds on the kinetics of conformational transitions of single bonds in trans-polybutadiene and poly(transpropenylene). For both molecules, a detailed discussion of the geometric and potential energy factors that determine the transition rates of the various types of single bonds is presented. Single bond...

This feature article discusses some selected aspects in the field of vibrational structure calculations based on vibrational self-consistent field, VSCF, and vibrational configuration interaction, VCI, theory. As the quality of such calculations depends strongly on the accuracy of the underlying multidimensional potential energy surface, PES, some techniques will be discussed to establish high-...

Aims. The objective is to obtain the best possible set of rotational (de)-excitation state-to-state and effective rate coefficients for temperatures up to 1500 K. State-to-state rate coefficients are presented among the 20 lowest levels of para-H2O with H2( j2 = 1) and Δ j2 = 0,+2, and among the 10 lowest levels of para-H2O with H2( j2 = 3) and Δ j2 = 0,−2. Methods. Calculations are performed w...