Degenerate topological line surface phonons in quasi-1D double helix crystal SnIP

  title={Degenerate topological line surface phonons in quasi-1D double helix crystal SnIP},
  author={Bo Peng and Shuichi Murakami and Bartomeu Monserrat and Tiantian Zhang},
  journal={npj Computational Materials},
Degenerate points/lines in the band structures of crystals have become a staple of the growing number of topological materials. The bulk-boundary correspondence provides a relation between bulk topology and surface states. While line degeneracies of bulk excitations have been extensively characterised, line degeneracies of surface states are not well understood. We show that SnIP, a quasi-one-dimensional van der Waals material with a double helix crystal structure, exhibits topological nodal… 
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