Figure 8.

(a) DOS of 3N^down and 3N^up SAMs at θ = ¹/₂, aligned at the average electrostatic energy across the SAM, E̅ (see Figure 3a). The thick black curves are Gaussian-convolutions (σ = 0.1 eV) of the results of the calculation. The insets show band charge-densities of the frontier states, and the band gap is indicated. It is determined from the onsets of the respective nonbroadened DOS peaks. (b) Energetic shifts of the HOMO, HOMO–1, and LUMO derived bands in a SAM of 3N^down (left) and 3N^up (right) molecules relative to the molecular eigenvalues upon increasing the SAM packing density θ. The energies are determined from the onsets of the respective peaks in the DOS. They are aligned at the left vacuum energy E_vac^left; the absolute molecular eigenvalues (approximated by θ = ¹/₆₄) are −6.52 eV (−6.57 eV), −7.02 eV (−6.74 eV), and −3.02 eV (−2.90 eV) for the π-HOMO, σ-HOMO, and LUMO of 3N^down (3N^up). (c) DOS of the full metal/SAM system projected onto the molecular region (PDOS) for the 3N^down and 3N^up SAMs, with broadening and insets as in part a.(118) Only a small fraction of metal atoms is shown. The Fermi energy is indicated as gray horizontal line.