Model of 3D LG Adsorbate

Vibrational spectra of adsorbed molecules have been studied in a lot of publications (see, e.g., the list of references in (Zhdanov 1988)). These data can be used for the modeling of two- or one-dimensional adsoiption wells. The information on the probabilities of energy relaxation through the interaction with phonon and electron subsystems of solid body is also available from the literature (Zhdcuiov 1988). 

If em adsorbed molecule is moving in electronically adiabatic potential well the model of two-dimensional anharmonic oscillator can be used for the description of its vibrational spectrum. This spectrum E(,n) (n = (ni,Ti2)) can be calculated by the numerical or analytical integration of the two-dimensional Schrodinger equation. The calculations of the transition probabilities e E, E) (or e(n, n)) for such oscillator have been performed with the help of the pertiu-bation theory or more sophisticated approaches. Provided these transition probabiUties e(n, n) are known for dense enough energy spectrum (AE ksT ), a diffusion model of energy relaxation may be used 

Dj = CjEj, Cj = const, pj = const. Within the approximation (7.1.2) the operator E(/c) becomes 

To include the intramolecular structure one has to consider the interaction of the intramolecular (rotational, vibrational, electronic) degrees of freedom with the translational motions (i.e. vibrations in the adsorption well). 

To take into account non-adiabatic effects induced by the avoided-crossing of different potential curves (see Fig. 3), one has to include strong interaction of several vibrational modes of the adsorbate. 

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