Rotation numbers, boundary forces and gap labelling
نویسندگان
چکیده
We review the Johnson–Moser rotation number and the K0-theoretical gap labelling of Bellissard for one-dimensional Schrödinger operators. We compare them with two further gap labels, one being related to the motion of Dirichlet eigenvalues, the other being a K1-theoretical gap label. We argue that the latter provides a natural generalization of the Johnson–Moser rotation number to higher dimensions. PACS number: 02.40.−k
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Gap labelling and the pressure on the boundary
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