Spotting structural defects in crystals from the topology of vibrational modes

TL;DR

This paper demonstrates that the topology of vibrational modes can be used to identify structural defects in crystals, linking vibrational patterns to dislocations, disclinations, and inclusions, similar to amorphous solids.

Contribution

It extends the topological defect identification method from amorphous to crystalline solids, revealing a direct connection between vibrational mode topology and structural defects.

Findings

Topology of vibrational modes predicts defect locations in crystals.

Structural defects in crystals show similar topological characteristics as in amorphous solids.

Vibrational mode analysis can identify dislocations, disclinations, and inclusions.

Abstract

Because of the inevitably disordered background, structural defects are not well-defined concepts in amorphous solids. In order to overcome this difficulty, it has been recently proposed that topological defects can be still identified in the pattern of vibrational modes, by looking at the corresponding eigenvector field at low frequency. Moreover, it has been verified that these defects strongly correlate with the location of soft spots in glasses, that are the regions more prone to plastic rearrangements. Here, we show that the topology of vibrational modes predicts the location of structural defects in crystals as well, including the cases of dislocations, disclinations and Eshelby inclusions. Our results suggest that in crystalline solids topological defects in the vibrational modes are directly connected to the well-established structural defects governing plastic deformations and present characteristics very similar to those observed in amorphous solids.