  The underlying structural disorder renders the concept of topological defects
in amorphous solids difficult to apply and hinders a first-principle
identification of the microscopic carriers of plasticity and of the regions
more prone to structural rearrangements ("soft spots"). Recently, it has been
proposed that well-defined topological defects can still be identified in
glasses, and correlated to local and global plasticity, by looking at the
eigenvector field or the particle displacement field. Nevertheless, all the
existing proposals and analyses are only valid in two spatial dimensions. In
this work, we propose the idea of using hedgehog topological defects to
characterize the plasticity of 3D glasses and to geometrically predict the
location of their soft spots. We corroborate our proposal by simulating a
Kremer-Grest 3D polymer glass, and by using both the normal mode eigenvector
field and the displacement field around large plastic events. Our results
confirm that a topological characterization of plasticity in glasses is
feasible, and provide a concrete realization of this program in 3D amorphous
systems.
