This study is motivated by recent applications of ultra-short laser pulses to the manipulation of structures on the atomic scale. It describes the energies and the time-scale needed to induce and to observe such changes. The structures adopted to this purpose are taken from the field of silicon nanotechnology and consist on monotaomic wires and small clusters of a columnar shape. These last ones are covered on both sides with an aluminum overlayer and can be regarded as the finite-size analogous of macroscopic electronic devices. The effect of laser is simply described as an increase of the kinetic energy in the nuclear subsystem. The calculations are based on real-time, real-space implementation of the semiempirical Hartree-Fock theory. The results show the occurrence of phenomena similar to recristallization and melting in the bulk and illustrate the dependence of these effects on the energy input and on the cluster size and composition.