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In this work we continue the study of the Weyl asymptotics of the distribution of eigenvalues of non-self-adjoint (pseudo)differential operators with small random perturbations, by treating the case of multiplicative perturbations in…

Spectral Theory · Mathematics 2009-12-02 Johannes Sjoestrand

We consider a magnetic Schr\"odinger operator $H^h$, depending on a semiclassical parameter $h>0$, on a compact Riemannian manifold. We assume that there is no electric field. We suppose that the minimal value $b_0$ of the intensity of the…

Spectral Theory · Mathematics 2013-11-26 Bernard Helffer , Yuri A. Kordyukov

We estimate the number of small eigenvalues of Schr\"odinger operators on Riemannian vector bundles over geometrically finite manifolds.

Differential Geometry · Mathematics 2024-12-24 Werner Ballmann , Panagiotis Polymerakis

We extend a result of Davies and Nath on the location of eigenvalues of Schr\"odinger operators with slowly decaying complex-valued potentials to higher dimensions. In this context, we also discuss various examples related to the…

Spectral Theory · Mathematics 2019-11-27 Jean-Claude Cuenin

We investigate the persistance of embedded eigenvalues under perturbations of a certain self-adjoint Schr\"odinger-type differential operator in $L^2(\mathbb{R};\mathbb{R}^n)$, with an asymptotically periodic potential. The studied…

Functional Analysis · Mathematics 2024-02-02 Sara Maad Sasane , Wilhelm Treschow

We consider a Schr\"odinger Operator with a matrix potential defined in $L_2^m(F)$ by the differential expression\begin{equation*} L(\phi(x))=(-\Delta+V(x))\phi(x) \end{equation*}and the Neumann boundary condition, where $F$ is the $d$…

Spectral Theory · Mathematics 2014-09-17 Sedef Karakłlłç , Setenay Akduman

In a first part of this paper we investigate the continuity (stability) of the spectrum of a class of non-local Schr\"odinger operators on varying the potentials. By imposing conditions of different strength on the convergence of the…

Analysis of PDEs · Mathematics 2022-11-21 Giacomo Ascione , József Lőrinczi

We study the Schroedinger operator with a constant magnetic field in the exterior of a compact domain in $\mathbb{R}^{2d}$, $d\geq 1$. The spectrum of this operator consists of clusters of eigenvalues around the Landau levels. We give…

Mathematical Physics · Physics 2015-05-13 Mikael Persson

We consider discrete one-dimensional Schroedinger operators whose potentials decay asymptotically like an inverse square. In the super-critical case, where there are infinitely many discrete eigenvalues, we compute precise asymptotics of…

Spectral Theory · Mathematics 2015-09-29 David Damanik , Gerald Teschl

This paper concerns spectral properties of linear Schr\"odinger operators under oscillatory high-amplitude potentials on bounded domains. Depending on the degree of disorder, we prove the existence of spectral gaps amongst the lowermost…

Numerical Analysis · Mathematics 2020-02-11 Robert Altmann , Patrick Henning , Daniel Peterseim

For one-dimensional Schroedinger operators with complex-valued potentials, we construct pseudomodes corresponding to large pseudoeigenvalues. Our (non-semi-classical) approach results in substantial progress in achieving optimal conditions…

Spectral Theory · Mathematics 2019-05-21 David Krejcirik , Petr Siegl

We use a classical result of Hildebrandt to establish simple conditions for the absence of eigenvalues of non-selfadjoint discrete and continuous Schr\"odinger operators on the boundary of their numerical range.

Spectral Theory · Mathematics 2012-06-13 Marcel Hansmann

We consider a magnetic Schr\"odinger operator $H^h$, depending on the semiclassical parameter $h>0$, on a two-dimensional Riemannian manifold. We assume that there is no electric field. We suppose that the minimal value $b_0$ of the…

Spectral Theory · Mathematics 2010-01-12 Bernard Helffer , Yuri A. Kordyukov

We obtain the asymptotic formulas for the eigenvalues and eigenfunctions of the Sturm-Liouville operators with general regular boundary conditions. Using these formulas, we find sufficient conditions on the potential q such that the root…

Spectral Theory · Mathematics 2013-06-07 Cemile Nur , O. A. Veliev

We give a survey of some results, mainly obtained by the authors and their collaborators, on spectral properties of the magnetic Schr\"odinger operators in the semiclassical limit. We focus our discussion on asymptotic behavior of the…

Spectral Theory · Mathematics 2008-12-31 Bernard Helffer , Yuri A. Kordyukov

We investigate the eigenvalues of perturbed spherical Schr\"odinger operators under the assumption that the perturbation $q(x)$ satisfies $x q(x) \in L^1(0,1)$. We show that the square roots of eigenvalues are given by the square roots of…

Spectral Theory · Mathematics 2010-09-07 Aleksey Kostenko , Alexander Sakhnovich , Gerald Teschl

We consider nonselfadjoint perturbations of semiclassical harmonic oscillators. Under appropriate dynamical assumptions, we establish some spectral estimates such as upper bounds on the resolvent near the real axis when no geometric control…

Mathematical Physics · Physics 2020-05-27 Victor Arnaiz , Gabriel Rivière

In this article we obtain the asymptotic formulas for the eigenvalues and eigenfunctions of the self-adjoint operator generated by a system of Sturm-Liouville equations with summable coefficients and the quasiperiodic boundary conditions.…

Spectral Theory · Mathematics 2007-05-23 O. A. Veliev

When an eigenvector of a semi-bounded operator is positive, we show that a remarkably simple argument allows to obtain upper and lower bounds for its associated eigenvalue. This theorem is a substantial generalization of Barta-like…

Spectral Theory · Mathematics 2009-11-11 Amaury Mouchet

We consider a semi-classical Schrodinger operator with a degenerate potential V(x,y) =f(x) g(y) . g is assumed to be a homogeneous positive function of m variables and f is a strictly positive function of n variables, with a strict minimum.…

Mathematical Physics · Physics 2008-12-17 Abderemane Morame , Francoise Truc