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arXiv · 1905.12649

Local formula for the $Z_2$ invariant of topological insulators

Zhi Li·Roger S. K. Mong
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Abstract

We proposed a formula for the $Z_2$ invariant for topological insulators, which remains valid without translational invariance. Our formula is a local expression, in the sense that the contributions mainly come from quantities near a point. Using almost commute matrices, we proposed a method to approximate this invariant with local information. The validity of the formula and the approximation method is proved.

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Zhi Li, Roger S. K. Mong. 2019-11-05. Local formula for the $Z_2$ invariant of topological insulators. https://doi.org/10.1103/physrevb.100.205101

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