Welsh eigenvalues of radially periodic Schrödinger operators
The authors find conditions under which the radially periodic Schrödinger operator in \(L_2(\mathbb{R}^2)\), defined by \(T= -\Delta+ V\), where \(V(x)= q(| x|)\) and \(q\) is even and periodic, has a nonempty lower spectrum. The case when \(q(r)= \cos(r)\) (Welsh eigenvalues) is considered separately.
scientific article; zbMATH DE number 1218652