LOW-DIMENSIONAL AND DISORDERED SYSTEMS Linear diatomic crystal: single-electron states and large-radius excitons

摘要: the quasi-one-dimensional large-radius exciton problem can be reduced to a 1D system of two quasi-particles with potential having Coulomb attraction tail. Due parity interaction states should split into odd and even series. In Ref. 10 we show that for bare screened potentials binding energy excitons in ground state well exceeds gap same work also discuss factors which prevent collapse single-electron isolated semiconducting single-walled carbon nanotubes SWCNTs. But electron-hole e-h thus corresponding energies may depend noticeably on electron hole charge distributions. It is therefore worthwhile ascertain whether effect seeming instability near inherent all semiconductors vacuum or maybe takes place only SWCNTs specific localization electrons holes at their surface weak screening by bound electrons. That why consider here simplest model semiconductor cylindrical symmetry, namely linear crystal atoms unit cell. The this are simply localized its axis. aim qualitative analysis mentioned. For study structure concerned, apply zero-range ZRP method 11,12 see Sec. II. matter results band states, obtained Refs. 13 14, appeared good accordance experimental data ab initio calculations related states. specificity use parameters mass, lattice taken from works nanotubes. 13,14 III obtain electrons, then largeradius spectrum vacuum. All these used IV, where present crystals different periods means structures. As it turns out, 2 – 5 times vacuum, negligible. Note result was within framework exactly solvable feasible parameters. Therefore, mentioned take not considered case but, most likely, other quasi-onedimensional