Figure 6. Linear chains of five and six DBs.

(a) STM topographs of the five-DB chain at +1.8, +1.4 and −1.4 V, respectively (15 pA; 4.5 × 2 nm²). (b) Line profiles taken along the DB structures as indicated for each of the images in a. (c) Simulated line profiles generated from linear combinations, Σc_i|ψ_i|², of the individual bound-state solutions to the five-DB system. (d) Five-DB potential well and the probability distributions of its bound-state wavefunctions, ψ₁ to ψ₇ with binding energies given in eV. (e–h) Repeat of panels a–d for a six-DB chain (images are 5.3 × 2 nm²). The coefficients c_i were calculated using c_i=e^−Ei/α where α=0.15 and 0.3 for filled and empty states, respectively, and E_i is the binding energy of the i-th state. For the low empty-state bias (+1.4 V) simulation of the five-DB, only contributions from ψ₄ and ψ₅ were included, whereas for the six-DB states ψ₅, ψ₆ and ψ₇ were included with c₇=1.5c₆ (see text).