A Schauder and Riesz Basis Criterion for Non-Self-Adjoint Schrödinger Operators with Periodic and Antiperiodic Boundary Conditions

Fritz Gesztesy, Vadim Tkachenko

Under the assumption that $V\in L^2([0,\pi ];dx)$, we derive necessary and sufficient conditions for (non-self-adjoint) Schrödinger operators $-d^2/d{x}^2+V$ in $L^2([0,\pi ];dx)$ with…