In the present work we study the influence of the unfolding procedure on the electronic level spacing statistics of silver nanoparticles (in their most stable configuration) with 923 and 2057 atoms, which were obtained employing molecular dynamics simulation with a tighet-binding potential. The results indicate that there is a strong dependence of the Brody parameter with the degree "n" of the polynomial used to make the unfolding procedure, especially for small n. For n=>6 the Brody parameter, independently of the nanoparticle sizes, remains almost constant. Thus, it was determined that the Brody parameter is close to the value corresponding to the Wiguer distribution, which is expected for systems in the metallic regime.

An alternative method to determine the critical cooling rate of materials has been developed by explaining the size and cooling rate dependences of physical properties of metallic nanoparticles through the scaling theory. This method has been applied to silver and copper nanoparticles which have been obtained by molecular dynamics simulations. The results reveal that our values for critical rate are close for each studied physical quantity. Thus, by taking the average among them, we obtain 6.2(8) × 1012 K/s for silver and 8.9(5) × 1012 K/s for copper. We have also found the threshold size of nanoparticle behavior is independent of the cooling rate.

In this paper we study the influence of cooling rate on the structural properties of silver nanowires with 1.6 nm of diameter. This study is done employing molecular dynamics methods with a tight-binding potential. The cooling rates used are in the range of 0.25-25 K/ps. The structural analysis of these systems is performed studying the pair correlation function and the pair analysis technique. The results indicate that the cooling rate affects significantly the structural properties of silver nanowires finding two representative rates, the rupture rate of 2.55 K/ps, where the nanowire is broken into two nanoparticles, and the collapse rate of 1.73 K/ps, where the two nanoparticles collapse to one spherical nanoparticle.

In the present work we determine the threshold of the nanoparticle behavior of copper nanoparticles by studying their structural and electronic properties. The studied nanoparticles contain from 13 to 8217 atoms and were obtained by molecular dynamics simulations using the Johnson potential for copper based on the embedded atom method. The results indicate that for small copper nanoparticles (o1000 atoms, 2.8 nm) the surface plays an important role in their physical properties. Whereas, for large nanoparticles (42000 atoms, 3.5 nm), with spherical-like external shape and large percentage of fcc-like local structure, this effect is negligible and their electronic character are similar to such expected in solid copper. Finally, it has also been shown that copper nanoparticles change their electronic character, from metallic to insulating, after increasing the strength of the chemical disor...