Our goal is to find an asymptotic behavior as n→∞ of orthogonal polynomials P n(z) defined by the Jacobi recurrence coefficients a n,b n. We suppose that the off-diagonal coefficients a n grow so rapidly that the series ∑a n −1 converges, that is, the Carleman condition is violated. With respect to diagonal coefficients b n we assume that −b n(a na n−1) −1/2→2β for some β ≠±1. The asymptotic formulas obtained for P n(z) are quite different from the case ∑a n −1=∞ when the Carleman condition is satisfied. In particular, if ∑a n −1<∞, then the phase factors in these formulas do not depend on the spectral parameter z∈C. The asymptotic formulas obtained in the cases |β |<1 and |β |>1 are also qualitatively different from each other. As an application of these results, we find necessary and sufficient conditions for the essential self-adjointness of the corresponding minimal Jacobi operator.

Original languageEnglish
Article number108648
Number of pages37
JournalJournal of Functional Analysis
Volume279
Issue number7
Early online date20 May 2020
DOIs
StatePublished - 15 Oct 2020

    Research areas

  • Jacobi matrices, Carleman condition, orthogonal polynomials, Asymptotics for large numbers, Orthogonal polynomials

    Scopus subject areas

  • Analysis

ID: 71379271