A useful formula for periodic Jacobi matrices on trees.
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- Record sourced from PubMed, PMID 38819999.
- Also identified by DOI 10.1073/pnas.2315218121 and PMC identifier 11161740.
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Abstract
We introduce a function of the density of states for periodic Jacobi matrices on trees and prove a useful formula for it in terms of entries of the resolvent of the matrix and its "half-tree" restrictions. This formula is closely related to the one-dimensional Thouless formula and associates a natural phase with points in the bands. This allows streamlined proofs of the gap labeling and Aomoto index theorems. We give a complete proof of gap labeling and sketch the proof of the Aomoto index theorem. We also prove a version of this formula for the Anderson model on trees.