Trajectory surface hopping model

By using this approach, it is possible to calculate vibrational state-selected cross-sections from minimal END trajectories obtained with a classical description of the nuclei. We have studied vibrationally excited H2(v) molecules produced in collisions with 30-eV protons [42,43]. The relevant experiments were performed by Toennies et al. [46] with comparisons to theoretical studies using the trajectory surface hopping model [11,47] fTSHM). This system has also stimulated a quantum mechanical study [48] using diatomics-in-molecule (DIM) surfaces [49] and invoicing the infinite-onler sudden approximation (lOSA). 

The trajectory surface hopping model of ion-molecule reaction dynamics has realized an impressive agreement between theory and experiment in this reaction, i.e. H+ + H2, and it provides the experimentalist with a realistic and workable theory to use in the comparison with and interpretation of experimental results. As reliable potential energy surfaces become available for other ion-molecule systems, we can expect further tests of this theory and its applicability to more complicated reactions. 

Each of the semi-classical trajectory surface hopping and quantum wave packet dynamics simulations has its pros and cons. For the semi-classical trajectory surface hopping, the lack of coherence and phase of the nuclei, and total time per trajectory are cons whereas inclusion of all nuclear degrees of freedom, the use of potentials direct from electronic structure theory, the ease of increasing accuracy by running more trajectories, and the ease of visualization of results are pros. For the quantum wave packet dynamics, the complexity of setting up an appropriate model Hamiltonian, use of approximate fitted potentials, and the... 

Recently, Garth Jones (UNSW) and his co-workers have described a semi-classical molecular dynamics (MD) model, which incorporates the trajectory surface hopping (TSH) method, that shows promise in investigating a number of important problems concerning the effects of molecular vibrations on the dynamics of ET reactions, including formally symmetry-forbidden ones. Essentially,... 

In difference to normal ground state thermal chemistry (ignoring chemiluminescence and bioluminescence), which is usually well described by the Born-Oppenheimer approximation, photochemistry usually require a non-adiabatic description for a qualitative and quantitative model to be possible. A number of techniques have been developed to address this problem. Out of these we find the semi-classical trajectory surface hopping (TSH) approach or more sophisticated approaches based on a nuclear... 

As explained above, the naive surface hopping model lets a classical trajectory running on an adiabatic potential siu face jumps to another at a specific point with a transition probability borrowed from other theories. Although... 

Another topic in the classical treatment of reactive collisions which has advanced considerably in recent years concerns the treatment of electronically nonadiabatic processes. Early work on this topic followed either the semiclassical complex trajectory method of George and Miller,or the more approximate surface hopping model of Tully and Preston.Recent work in this field by McCurdy, Meyer, and Miller " has attempted to develop a purely classical description of the electronic degrees of freedom, thereby replacing the many-surface aspect of the dynamics with extra classical degrees of freedom (one for each surface beyond the first) which represent the collective electronic motions to which the nuclear motions can couple to cause transitions. This means that a multiple-surface problem can now be treated by standard" trajectory methods, which is a considerable computational simplification. Applications to the f ( Pi/2) 2... 

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