Model Simulations
Classical Trajectory Calculations
|
A
powerful tool in interpreting experimental results is computational modeling.
We have developed classical trajectory codes to model hyperthermal molecule/surface
reactions under our experimental conditions. The simulations range from calculations
involving large slabs of harmonically coupled surface atoms to simpler planar
models for treating impulsive energy transfer. With the goal of providing a
more complete picture of the operative dynamics, we have performed classical
trajectory simulations for some of the aforementioned experimental studies and
have achieved quantitative results in many cases.
A
representative movie is shown below for the scattering of Br on a three-fold
hollow site on Pt(111). The surface deformation alters the charge transfer probability
for the daparting Br projectile.
Click
on frames to see quick time movies of a trajectory for 25 eV Br striking a 3-fold
hollow site on Pt111). The movies differ only in the camera angle.
For
more information, see:
- Martin, J. S.,
Feranchak, B. T., Morris, J. R., Greeley, J. N., and Jacobs, D. C. (1996)
"Simplified Classical Trajectory Model of Dissociative Scattering on
Surfaces: Role of Incident Vibrational and Translational Energies," Journal
of Physical Chemistry 100, 1689-1697.
- Greeley, J.
N., Martin, J. S., Morris, J. R., and Jacobs, D. C. (1995) "Scattering
Aligned NO+ on Ag(111): The Effect of Internuclear-Axis Direction
on NO- and O- Product Formation," Journal of
Chemical Physics 102, 4996-5011.
- Martin, J. S.,
Greeley, J. N., Morris, J. R., Feranchak, B. T., and Jacobs, D. C. (1994)
"Scattering state-selected NO+ on GaAs(110): The Effect of
Translational and Vibrational Energy on NO- and O- product
formation," Journal of Chemical Physics 100, 6791-6812.
- Morris, J.
R., Martin, J. S., Greeley, J. N., and Jacobs, D. C. (1995) "Surface
Site Dependence to Negative Ion Formation in Dissociative Scattering,"
Surface Science 330, 323-336.
- Morris, J.
R., Kim, G., Barstis, T., Mitra, R., and Jacobs, D. C. (1997) "Dynamics
of Dissociative Scattering: Hyperthermal Energy Collisions of State-Selected
OCS+ on Ag(111)," Journal of Chemical Physics 107,
6448-6459.
Quantum Wavepacket Simulations
|
In a collaboration
with Prof. David Tannor, we have applied a time-dependent quantum mechanics
formalism to accurately simulate both the electron transfer dynamics and the
nuclear motion associated with hyperthermal energy ion/surface reactions. These
wavepacket calculations proved successful in quantitatively simulating the aforementioned
dependence of the scattered O- yield on incident NO+ vibrational
quanta. Computational modeling, in tandem with state-selected ion/surface experiments,
have provided unprecedented details to the reaction mechanisms operative in
molecular ion/surface systems.
For more information,
see:
- Qian, J., Jacobs,
D. C., and Tannor, D. J. (1995) "A Novel Wavepacket Description of Electron
Transfer and Dissociation in Molecule/Surface Reactive Scattering," Journal
of Chemical Physics 103, 10764-10778.