Influence of two-dimensional discrete breathers on the macroscopic properties of fcc metals

Abstract

Delocalized nonlinear vibrational modes (DNVMs) in crystals are precise solutions to the equations governing atomic motion that are determined solely by the symmetry of the lattice. This study investigates the influence of two-dimensional discrete breathers (DBs) excited using four one-component DNVMs on the macroscopic properties of three-dimensional fcc single crystals of Al, Cu, and Ni. All results were obtained using molecular dynamics simulations. Key findings include the observation that the lifetime of two-dimensional DBs is significantly influenced by both the symmetry of the DNVM and the initial oscillation amplitude. The two-dimensional DBs exhibit hard-type nonlinearity, characterized by an increase in oscillation frequency with increasing initial amplitude. The excitation of the DBs leads to a reduction in the crystal's heat capacity, which becomes more pronounced with increasing amplitude. The presence of two-dimensional DBs induces thermal expansion within the crystal, suggesting an impact on the mechanical properties of the material. This research provides new insights into the role of DBs, in influencing the macroscopic properties of fcc metals.

Graphical abstract