Computing topological invariants without inversion symmetry
Abstract
We consider the problem of calculating the weak and strong topological indices in noncentrosymmetric time-reversal (T) invariant insulators. In 2D we use a gauge corresponding to hybrid Wannier functions that are maximally localized in one dimension. Although this gauge is not smoothly defined on the two-torus, it respects the T symmetry of the system and allows for a definition of the Z_2 invariant in terms of time-reversal polarization. In 3D we apply the 2D approach to T-invariant planes. We illustrate the method with first-principles calculations on GeTe and on HgTe under [001] and [111] strain. Our approach differs from ones used previously for noncentrosymmetric materials and should be easier to implement in ab initio code packages.
Cite
@article{arxiv.1102.5600,
title = {Computing topological invariants without inversion symmetry},
author = {Alexey A. Soluyanov and David Vanderbilt},
journal= {arXiv preprint arXiv:1102.5600},
year = {2011}
}
Comments
revised version, accepted to PRB