Abstract
We consider Schr\"odinger operators in L²(R^ν), ν=2,3, with the interaction in the form on an array of potential wells, each on them having rotational symmetry, arranged along a curve Γ. We prove that if Γ is a bend or deformation of a line, being straight outside a compact, and the wells have the same arcwise distances, such an operator has a nonempty discrete spectrum. It is also shown that if Γ is a circle, the principal eigenvalue is maximized by the arrangement in which the wells have the same angular distances. Some conjectures and open problems are also mentioned.