Collective Motion of Atoms in Metals by First Principles Calculations

Abstract

AbstractFundamental information on the collective motion of atoms can be learned by tracing imaginary phonon modes in deformed crystals. This should be useful to investigate the atomic process of plaston in a logical manner. Here, we summarize our works on the collective motion of atoms in unary metallic crystals examined by first principles phonon calculations. A simple algorithm for automated searching of the structural transition pathway following the imaginary phonon modes has been constructed. We first show the construction of structure evolution diagrams in Cu, Mg, Ti, and Hf by taking a simple cubic (SC) structure as a starting structure. The pathway corresponds to a route connecting initial and final structures without any energy barrier. Effects of the hydrostatic pressure on the diagram have been examined as well. In the second part, the collective motion of atoms in HCP-Ti under homogeneous shear deformation corresponding to the {$$10\overline{1} 2$$ 10 1 ¯ 2 } twinning mode is shown. The structural transition pathway from the parent to twin, which is widely accepted as the “shuffling”, is shown in detail.