We develop a robust full-Brillouin zone soft-phonon-searching algorithm, with outstanding accuracy and efficiency in pinpointing general phonon instability within the joint material-reciprocal spaces in crystals. By combining finite-element modeling with embedded phonon algorithm and atomistic simulation, we show how a zone-boundary soft phonon is first triggered in a perfect aluminum crystal under nanoindentation, which subsequently leads to a transient new crystal phase and ensuing nucleation of a deformation twin. We propose a two-stage mechanism governing the transformation of unstable short-wave phonons into lattice defects, fundamentally different from that initially triggered by soft long-wavelength phonons.
- Xiaohui Liu
- Jianfeng Gu
- Ju Li
