Antiscreening and exciton binding in quasi-one-dimensional systems

We predict antiscreening of the electron-hole interaction at large distances, independent of the distribution of the electronic response across the cross section of a quasi-one-dimensional (1D) wire system and of the chosen 1D hydrogen potential. The transition between screening and antiscreening is governed by the 1D static electronic polarizability alpha(1D) and the wire radius R, and is described through a 1D Rytova-Keldysh-like potential. The enhancement of the exciton binding is demonstrated over a wide parameter range of alpha(1D) and R, yielding a phase diagram that separates regions of exciton binding dominated by electronic polarization from those where antiscreening enforces stronger binding. Luttinger-liquid behavior is identified. Binding effects and (anti)screening are explicitly discussed for atomic wires based on MgN2, S-3, Te-3, As2S3, and Bi2Te3.