It is known that a purely off-diagonal Jacobi operator with coefficients [formula] has a purely absolutely continuous spectrum filling the whole real axis. We show that a 2-periodic perturbation of these operators creates a non trivial gap in the spectrum.
In this paper, we consider periodic Schrodinger operators on the dumbbell-like metric graph, which is a periodic graph consisting of lines and rings. Let one line and two rings be in the basic period. We see the relationship between the structure of graph and the band-gap spectrum.
3
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
In the paper we prove the lower bound estimate λD2 −λDD1≥c(λD1)−d−α(diamD−d−α) for the spectral gap of the Dirichlet fractional Laplacian (−(−Δ)α/2) on an arbitrary bounded open set D⊂ Rd.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.