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<p style="margin-top:0;margin-bottom:0">Hello,</p>

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<p style="margin-top:0;margin-bottom:0">I don't quite understand how can I get the topological <span>invariants, like Z2 and Chern, within a 2D system? I'm feeling puzzled when building the surface. </span></p>

<p style="margin-top:0;margin-bottom:0"><span>BTW I'm using vasp. </span></p>

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<p style="margin-top:0;margin-bottom:0"><span>Thank you,</span></p>

<p style="margin-top:0;margin-bottom:0"><span>Patric</span></p>

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