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Step 3. Molecular junction between Au electrodes Current-Voltage (I-V) Characteristics

Au. V. I. Au. Step 3. Molecular junction between Au electrodes Current-Voltage (I-V) Characteristics Periodic QM (DFT) with surface Green’s function formalism. Kim, Jang, YHJ, Goddard III, Phys. Rev. Lett., 95, 156801 (2005). m. 1. 2. G 1. G 2. T(E,V).

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Step 3. Molecular junction between Au electrodes Current-Voltage (I-V) Characteristics

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  1. Au V I Au Step 3. Molecular junction between Au electrodes Current-Voltage (I-V) Characteristics Periodic QM (DFT) with surface Green’s function formalism Kim, Jang, YHJ, Goddard III, Phys. Rev. Lett., 95, 156801 (2005)

  2. m 1 2 G1 G2 T(E,V) I-V :DFT + Green’s Function + Landauer formalism Density-functional theory (Hohenberg-Kohn-Sham) “Extended molecule” + separate bulk electrode calc. -> H, S Non-Eqm. Green’s ftn. Formalism (Fisher-Lee) self-energy broadening Ballistic transport theory (Landauer, Buttiker) Calculated with SeqQuest periodic DFT code (Peter Schultz, Sandia)

  3. V V 0(EF) Au Au Au Au Au Au V=0 Small V Large V I=0 I=0 I0

  4. TTF DNP Au Au Au TTF DNP Au Au TTF DNP Au Au TTF DNP Au Implication of QM to switching mechanism (TTF)(DNP) “finger only” [2]rotaxane [2]catenane CBPQT (TTF)(CBPQT)(PF6)4(DNP) “CBPQT@TTF” CBPQT @TTF No HOMO level close to EF (TTF)(DNP)(CBPQT)(PF6)4 “CBPQT@DNP” CBPQT @DNP TTF HOMO level close to EF

  5. Au Au Key components between Au(111) slabs ~CBPQT@TTF ~CBPQT@DNP Rotaxane ~ Catenane ~ sum-up of components TTF TTF+CBPQT DNP DNP+CBPQT 1.5 nm

  6. TTF+CBPQT TTF DNP DNP+CBPQT T (E) T (E) -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 E-EF (eV) E-EF (eV) TTF TTF+CBPQT DNP DNP+CBPQT ~CBPQT@DNP ~CBPQT@TTF Switch ON Switch OFF Transmission within the energy window

  7. Model junction: [2]Catenane between Au(111) slabs Folded rotaxane ~ Catenane CBPQT@TTF “Green” state CBPQT@DNP “Red” state

  8. Model: -stacked components between Au(111) (TTF)(CBPQT)(PF6)4:(DNP) “CBPQT@TTF” 1.8 nm 0.2 – 0.3 V (choice in experiments) CBPQT@DNP: Switch ON CBPQT@TTF: Switch OFF ON/OFF ratio ~5 (agreement with experiments) ON OFF 1.8 nm (TTF):(DNP)(CBPQT)(PF6)4 “CBPQT@DNP”

  9. (2) MD • Summary • Electronic structure of key components: QM •  Role of the ring 1: provide low-lying LUMO •  Role of the ring 2: stabilize energy level of station •  -orbitals dominant around HOMO-LUMO • (2) SAM packing on Au(111): MD simulation Coverage-dependent conformation • (3) I-V Calculation: periodic QM + Green’s function formalism • Au(111) - Model catenane/fully-folded-rotaxane - Au(111) (1) QM (3) Periodic QM + I-V

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