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Figure 6. (a) High resolution (12 x 12 nm’, Vsample = 0.040 V, J = 18 nA) and (b) large scale (30 x 30 nm’, Vsample = —9.050 V, J = 18 nA) STM images of the (1 4, 4 —3) phase obtained after the deposition of 4 ML of FePc on Ag(110). In panel a, the STM features have been evidenced with black lines for the topmost layer and with white lines for the underlying layer. The (1 4, 4 —3) superstructure unit cell is indicated in panel a. The inset in panel b shows the stacking of FePc units in the multilayer phase.

Figure 6 (a) High resolution (12 x 12 nm’, Vsample = 0.040 V, J = 18 nA) and (b) large scale (30 x 30 nm’, Vsample = —9.050 V, J = 18 nA) STM images of the (1 4, 4 —3) phase obtained after the deposition of 4 ML of FePc on Ag(110). In panel a, the STM features have been evidenced with black lines for the topmost layer and with white lines for the underlying layer. The (1 4, 4 —3) superstructure unit cell is indicated in panel a. The inset in panel b shows the stacking of FePc units in the multilayer phase.

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TABLE 1: Computational Results on the c(10 x 4) 1 ML Phase for the On-Top and Short-Bridge Minima’ “ Adsorption energies (Eas) are given in eV/molecule. Fe atom heights (Hp) are in nm. AEjus = Eas (On Top) - Eas (Short Bridge). Energies are in eV, distances in nm.
TABLE 1: Computational Results on the c(10 x 4) 1 ML Phase for the On-Top and Short-Bridge Minima’ “ Adsorption energies (Eas) are given in eV/molecule. Fe atom heights (Hp) are in nm. AEjus = Eas (On Top) - Eas (Short Bridge). Energies are in eV, distances in nm.
Figure 1. STM images (a. 6.8 x 7.4 nm’, Veample = +0.037 V, J = 0.05 nA; c. 30 x 30 nm’, Veample = 0.36 V, 1 = 0.2 nA; d. 6.8 x 7.4 nm’, Veample = +0.4 V, J = 0.7 nA; f. 35 x 35 nm’, Vsample = —0.6 V, J = 0.1 nA) of samples with FePc coverage <1 ML. Main crystallographic axes and overlayer unit cells are shown. Schemes indicating the alternating rows (A and B) with two different molecular orientations are shown in panel d. Atomic models of the c(10 x 4) and p(10 x 4) phases are shown in panels b and e, respectively. The Ag rows are clearly visible in the upper part of panel c, that is not covered by FePe molecules. The registry between FePc-related STM features and the Ag substrate is evidenced: black lines correspond to the troughs between adjacent Ag close-packed rows aligned with the [110] substrate direction. In panel a, white circles highlight several intermolecular tunneling features.
Figure 1. STM images (a. 6.8 x 7.4 nm’, Veample = +0.037 V, J = 0.05 nA; c. 30 x 30 nm’, Veample = 0.36 V, 1 = 0.2 nA; d. 6.8 x 7.4 nm’, Veample = +0.4 V, J = 0.7 nA; f. 35 x 35 nm’, Vsample = —0.6 V, J = 0.1 nA) of samples with FePc coverage <1 ML. Main crystallographic axes and overlayer unit cells are shown. Schemes indicating the alternating rows (A and B) with two different molecular orientations are shown in panel d. Atomic models of the c(10 x 4) and p(10 x 4) phases are shown in panels b and e, respectively. The Ag rows are clearly visible in the upper part of panel c, that is not covered by FePe molecules. The registry between FePc-related STM features and the Ag substrate is evidenced: black lines correspond to the troughs between adjacent Ag close-packed rows aligned with the [110] substrate direction. In panel a, white circles highlight several intermolecular tunneling features.
Figure 2. Simulated STM image (3.1 x 3.1 nm’, Vsample = 0.4 V) of the c(10 x 4) ML phase of FePc/Ag(110) assuming the on-top adsorption site (see text), obtained within the Tersoff-Hamann ap- proximation on the DFT-D’ optimized superstructure. The contour increment is 0.04 nm.
Figure 2. Simulated STM image (3.1 x 3.1 nm’, Vsample = 0.4 V) of the c(10 x 4) ML phase of FePc/Ag(110) assuming the on-top adsorption site (see text), obtained within the Tersoff-Hamann ap- proximation on the DFT-D’ optimized superstructure. The contour increment is 0.04 nm.
Figure 3. Electron density difference (Ap) plots of the on-top equilibrium configuration (see text). Red/blue isosurfaces indicate regions of charg accumulation/depletion. In panel a, the displayed isosurfaces are +6.7 x 107‘ e/ap°. In the side views, Ap is sectioned as shown by the dashed an dotted-dashed lines in the top view in panel a. Panels a—c refer to the DFT-D’ calculation, whereas panels d and e show the full DFT-D result:
Figure 3. Electron density difference (Ap) plots of the on-top equilibrium configuration (see text). Red/blue isosurfaces indicate regions of charg accumulation/depletion. In panel a, the displayed isosurfaces are +6.7 x 107‘ e/ap°. In the side views, Ap is sectioned as shown by the dashed an dotted-dashed lines in the top view in panel a. Panels a—c refer to the DFT-D’ calculation, whereas panels d and e show the full DFT-D result:
Figure 4. Time-lapsed imaging sequence (At © 2 min) of the p(10 x 4) phase (7.7 x 8.4 nm?, Veample = —90.40 V, J = 0.03 nA). Black bordered shapes represent FePc molecules and highlight their rotation and the consequent A/B rows switching.
Figure 4. Time-lapsed imaging sequence (At © 2 min) of the p(10 x 4) phase (7.7 x 8.4 nm?, Veample = —90.40 V, J = 0.03 nA). Black bordered shapes represent FePc molecules and highlight their rotation and the consequent A/B rows switching.
Figure 5. Potential energy surface for the unsupported ML. Energies are in eV/molecule. The dashed line shows the minimum energy path for the transition between the two configurations of the p(10 x 4) phase. The upper panel shows the energy barrier E, along the path for the unsupported ML (red dashed line) and for the Ag-supported ML in the DFT-D’ framework (black full line), respectively. The geometries of some relevant configurations are sketched in the panels on the right, where also the meaning of the angles a and / is shown. Angles are in degrees.
Figure 5. Potential energy surface for the unsupported ML. Energies are in eV/molecule. The dashed line shows the minimum energy path for the transition between the two configurations of the p(10 x 4) phase. The upper panel shows the energy barrier E, along the path for the unsupported ML (red dashed line) and for the Ag-supported ML in the DFT-D’ framework (black full line), respectively. The geometries of some relevant configurations are sketched in the panels on the right, where also the meaning of the angles a and / is shown. Angles are in degrees.
Figure 7. Structural relationship between the c(10 x 4) ML phase and the (1 4, 4 —3) bilayer/multilayer FePc phase on Ag (110). Substrate A atoms are represented by white circles. Only the Fe atoms of the FePc molecules (red for c(10 x 4); blue for (1 4, 4 —3)) are shown for clarity The respective unit cells are highlighted by dashed lines. The (20 4, 5 —18) coincidence cell between the two superstructures (full black line) i shown. Black arrows mark the shortest molecular displacements required to accomplish the structural transition. One extra molecule per coincidenc unit cell (circled) is needed to account for the higher density of the thicker phase.
Figure 7. Structural relationship between the c(10 x 4) ML phase and the (1 4, 4 —3) bilayer/multilayer FePc phase on Ag (110). Substrate A atoms are represented by white circles. Only the Fe atoms of the FePc molecules (red for c(10 x 4); blue for (1 4, 4 —3)) are shown for clarity The respective unit cells are highlighted by dashed lines. The (20 4, 5 —18) coincidence cell between the two superstructures (full black line) i shown. Black arrows mark the shortest molecular displacements required to accomplish the structural transition. One extra molecule per coincidenc unit cell (circled) is needed to account for the higher density of the thicker phase.
TABLE 2: Computational Results on 1 ML FePc Arranged in the (1 4, 4 —3) Phase’ “ Adsorption energies (Eqs, in eV/molecule) and Fe atom height (Age, in A) are reported. AF yas = Eyas (on top) — Exas (short bridge). Energies are in eV and distances in nm.
TABLE 2: Computational Results on 1 ML FePc Arranged in the (1 4, 4 —3) Phase’ “ Adsorption energies (Eqs, in eV/molecule) and Fe atom height (Age, in A) are reported. AF yas = Eyas (on top) — Exas (short bridge). Energies are in eV and distances in nm.
TABLE 3: Comparison of the Formation Energies (E,,,) of the OT-c(10 x 4) and SB-(1 4, 4 —3) Models, of the Relative Film Cohesion Energies (£,,.,) and of the Surface-Film Adhesion Energies (E,q,) and Their Density-Weighted Analogues ¢ (See Text)“ “ E values are in eV/molecule, whereas ¢ values are in eV/nm*. AE are defined as E[c(10 x 4)] — E[(1 4, 4 —3)], ie., for AE > 0 the denser (1 4, 4 —3) packing is favored. An equivalent definition and meaning holds for Ae.
TABLE 3: Comparison of the Formation Energies (E,,,) of the OT-c(10 x 4) and SB-(1 4, 4 —3) Models, of the Relative Film Cohesion Energies (£,,.,) and of the Surface-Film Adhesion Energies (E,q,) and Their Density-Weighted Analogues ¢ (See Text)“ “ E values are in eV/molecule, whereas ¢ values are in eV/nm*. AE are defined as E[c(10 x 4)] — E[(1 4, 4 —3)], ie., for AE > 0 the denser (1 4, 4 —3) packing is favored. An equivalent definition and meaning holds for Ae.
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