Abstract
The Neumann-Poincare operator is a boundary-integral operator associated with harmonic layer potentials. This article proves the existence of eigenvalues within the essential spectrum for the Neumann-Poincar\'e operator for certain Lipschitz curves in the plane with reflectional symmetry, when considered in the functional space in which it is self-adjoint. The proof combines the compactness of the Neumann-Poincare operator for curves of class $C^{2,\alpha }$ with the essential spectrum generated by a corner. Eigenvalues corresponding to even (odd) eigenfunctions are proved to lie within the essential spectrum of the odd (even) component of the operator when a $C^{2,\alpha }$ curve is perturbed by inserting a small corner.
Citation
Wei Li. Stephen P. Shipman. "Embedded eigenvalues for the Neumann-Poincare operator." J. Integral Equations Applications 31 (4) 505 - 534, 2019. https://doi.org/10.1216/JIE-2019-31-4-505
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