Computer simulation by the quantum mechanical time-dependent wavepacket method, especially for atom/molecule-solid-surface interaction

摘要

Thermal energy atomic scattering (TEAS) on solid surfaces forms the basis of a useful experimental method for obtaining information about the structure, disorder and phonon spectra of the solid surface. The probe particles (usually He atoms) can spend a relatively long time near the solid surface in the interaction region. The dynamics of the interaction processes cannot be investigated directly at present. However, an appropriate physical model of the interaction fitted to the intensity distribution of the scattering may be suitable for use in investigating the interaction processes theoretically, by computer simulation. The present work emphasizes this computer simulation method. For an actual computer simulation, the detector region TEAS experimental method must be appropriate. Moreover a theoretical model for the TEAS (e.g. a one-particle quantum mechanical wavepacket model governed by the time-dependent Schrodinger equation (TDSE)) and a numerical method for solving the TDSE are necessary. The state functions of the consecutive time steps provide enough information to produce, an 'animation' displaying the dynamics of the interaction processes. An 'animation' is a series of snapshots of e.g. the probability density function (PDF), taken in rapid succession. The sequence of these snapshots provides a 'movie' of the PDF time evolution. Applications, physical models, numerical solution procedures and simulation techniques, relating to the time-dependent wavepacket (TDWP) method are overviewed in the present contribution-especially for the case of TEAS and molecular beam scattering. Several relevant applications of the TDWP method-in the case of TEAS-are discussed (to scattering on ordered, stepped and adsorbed surfaces, the intensity distribution as a function of transfer width, resonant adsorption and trapping, classical and quantum chaos, scattering from vibrating surfaces). Preliminary results on the quantum chaos in TEAS are presented for the first time. The theoretical and computational background (the TDWP and coupled channel methods) as well as applications (to diffraction probability, sticking probability, dissociative adsorption, the steering effect, inelastic channels) of six-dimensional molecule/surface dynamics calculations are described. [References: 157]