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Slide title
The Wannier state from the nth band centered around site j is denoted by |w(n)(j)⟩ . Consider the Wannier states from different bands, n'≠n, and for different positions, j'≠j, i.e., |w(n')(j)⟩, |w(n)(j')⟩. Which of the overlaps is guaranteed to be zero by construction, the one between different bands, or the one between different positions?
a) Only the firstb) Only the secondc) Neither the one nor the secondd) Both