The scattering of atoms from surfaces is studied within the classical Wigner formalism. A new analytical expression is derived for the angular distribution and its surface temperature dependence. The expression is valid in the limit of weak coupling between the vertical motion with respect to the surface and the horizontal motion of the atom along the periodic surface. The surface temperature dependence is obtained in the limit of weak coupling between the horizontal atomic motion and the surface phonons. The resulting expression, which takes into account the surface corrugation, leads to an almost symmetric double peaked angular distribution, with peaks at the rainbow angles. The analytic expression agrees with model numerical computations. It provides a good qualitative description for the experimentally measured angular distribution of Ne and Ar scattered from a Cu surface.

A new scheme for the estimation of aggregate chemical potential and hardness is introduced and compared with the results of ab initio calculations for the aggregates as well as with the results obtained by employing various other combination schemes. Numerical results show that this new scheme provides better estimates of electronic chemical potential as well as comparable results for hardness with other addition schemes.

We investigate di erent mechanisms for the control of directed transport of particles on twodimensional periodic and symmetric substrates, based on the application of a crossed static and a bi-harmonic (harmonic mixing) ÿeld. We focus on inertial systems in the low friction regime, using a prototypical model for atom-surface di usion, and demonstrate that a proper control of current reversals can be achieved at moderate ÿeld strengths by tuning either the static ÿeld or changing the relative phase of the harmonic mixing signal, respectively.

The quantum-classical correspondence is studied for a periodically driven quartic oscillator exhibiting integrable and chaotic dynamics, by studying the Bohmian trajectory of the corresponding "classical" Schrödinger equation. Phase plots and the Kolmogorov-Sinai entropy are computed and compared with the classical trajectory as well as the Bohmian trajectory obtained from the time dependent Schrödinger equation. Bohmian mechanics at the classical limit appears to mimick the behavior of a dissipative dynamical system.