Energetics of fcc and decahedral nanowires of Ag, Cu, Ni, and C60: A quenched molecular dynamics study

The energetics of nanowires of several materials is studied by quenched molecular dynamics with the aim of comparing wires pertaining to two different types of structures, fcc and pentagonal, which are expected to be among the most favorable ones for wires of intermediate thickness. A detailed study is made in the case of nickel, copper, and silver wires. These metals are modeled by many-body semiempirical potentials developed within the second-moment approximation to the tight-binding model. For these metals, it turns out that the best pentagonal wires are always those including Marks truncations, but the fcc wires are more favorable than the pentagonal ones in any size range. In order to ascertain whether there could be systems where pentagonal wires are more stable than the fcc ones, also two extreme examples are treated, one with extremely soft interparticle interactions (a model for sodium) and one with very sticky interactions (a model for C60molecules). Only in the case of the model for sodium, there is a range at small thickness where pentagonal wires are slightly lower in energy than fcc wires.