TY - JOUR T1 - Numerical Approaches to Compute Spectra of Non-Self Adjoint Operators and Quadratic Pencils AU - Aboud , Fatima AU - Jauberteau , François AU - Moebs , Guy AU - Robert , Didier JO - Journal of Mathematical Study VL - 1 SP - 12 EP - 44 PY - 2020 DA - 2020/03 SN - 53 DO - http://doi.org/10.4208/jms.v53n1.20.02 UR - https://global-sci.org/intro/article_detail/jms/15206.html KW - Nonlinear eigenvalue problems, spectra, pseudospectra, finite difference methods, Galerkin spectral method, Hermite functions. AB -

In this article we are interested in the numerical computation of spectra of non-self adjoint quadratic operators. This leads to solve nonlinear eigenvalue problems. We begin with a review of theoretical results for the spectra of quadratic operators, especially for the Schrödinger pencils. Then we present the numerical methods developed to compute the spectra: spectral methods and finite difference discretization, in infinite or in bounded domains. The numerical results obtained are analyzed and compared with the theoretical results. The main difficulty here is that we have to compute eigenvalues of strongly non-self-adjoint operators which are very unstable.