Stability of the free boundary Willmore problem
Anna Dall'Acqua, Fabian Rupp, Reiner Schätzle, Manuel Schlierf
TL;DR
The paper develops a new Łojasiewicz–Simon gradient inequality on analytic Banach manifolds and applies it to the Willmore problem with free boundary. By constructing generalized Gaussian coordinates and reformulating the Willmore energy and its boundary conditions in this framework, the authors establish a LS inequality for free boundary surfaces and prove stability and rigidity results. This yields global existence and convergence of the free boundary Willmore flow near local minimizers and a local rigidity statement near free boundary minimal surfaces, with quantitative stability estimates tied to the energy deficit. The approach provides a robust, diffeomorphism-invariant toolkit for higher-order free boundary variational problems and their gradient flows.
Abstract
We study the Willmore problem with free boundary by means of a new Łojasiewicz-Simon gradient inequality for functionals on infinite dimensional manifolds. In contrast to previous works, we do not rely on a gradient-like representation of the Fréchet derivative, but merely on an inequality. For the free boundary Willmore flow, we prove that solutions starting sufficiently close to a local minimizer exist for all times and converge. In the static setting, we prove quantitative stability of free boundary Willmore immersions and a local rigidity result in a neighborhood of free boundary minimal surfaces.
