Electrostatically driven energy shift of molecular orbitals of benzene and nicotine in carbon nanotube gaps

Djurišić, Ivana; Dražić, Miloš S.; Tomović, Aleksandar Ž.; Jovanović, V. D.; Žikić, Radomir

doi:10.1007/s11051-021-05139-y

Cited by 2 publications

(6 citation statements)

References 38 publications

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“…As a rule of thumb, if the orbital is on the left (right) compared to the gap center, its energy would increase (decrease) with the increment of bias, with the variation more pronounced if the orbital location is further from the gap center (Figures 2b and 3). One could observe such behavior in other works [19,20,29]. The energy variation of orbitals of DNA nucleotides within the graphene−hBN heterostructure nanogap [19] complies with this rule of thumb.…”

Section: Discussionsupporting

confidence: 60%

“…In the weak pinning (WP) regime, the bias dependence of (frontier) orbital energies is driven mainly by the empty gap electrostatic potential energy E P and their spatial positions in the gap [29]. Figure 1 presents the spatial distribution of frontier orbitals of four DNA nucleotides.…”

Section: Empty Gap Properties and The Weak Pinningmentioning

confidence: 99%

“…We have previously shown, using density functional theory (DFT) and non-equilibrium Green's functions (NEGF), the existence of two different regimes of bias dependence of the frontier orbitals in molecular junctions: the strong and the weak pinning [18,29]. The former refers to the classical meaning of pinning: bias variations of the molecular orbital energy and the electrochemical potential of anelectrode are the same.…”

Section: Introductionmentioning

confidence: 99%

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Predicting Finite-Bias Tunneling Current Properties from Zero-Bias Features: The Frontier Orbital Bias Dependence at an Exemplar Case of DNA Nucleotides in a Nanogap

et al. 2021

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The electrical current properties of single-molecule sensing devices based on electronic (tunneling) transport strongly depend on molecule frontier orbital energy, spatial distribution, and position with respect to the electrodes. Here, we present an analysis of the bias dependence of molecule frontier orbital properties at an exemplar case of DNA nucleotides in the gap between H-terminated (3, 3) carbon nanotube (CNT) electrodes and its relation to transversal current rectification. The electronic transport properties of this simple single-molecule device, whose characteristic is the absence of covalent bonding between electrodes and a molecule between them, were obtained using density functional theory and non-equilibrium Green’s functions. As in our previous studies, we could observe two distinct bias dependences of frontier orbital energies: the so-called strong and the weak pinning regimes. We established a procedure, from zero-bias and empty-gap characteristics, to estimate finite-bias electronic tunneling transport properties, i.e., whether the molecular junction would operate in the weak or strong pinning regime. We also discuss the use of the zero-bias approximation to calculate electric current properties at finite bias. The results from this work could have an impact on the design of new single-molecule applications that use tunneling current or rectification applicable in high-sensitivity sensors, protein, or DNA sequencing.

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Section: Discussionsupporting

confidence: 60%

Section: Empty Gap Properties and The Weak Pinningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Predicting Finite-Bias Tunneling Current Properties from Zero-Bias Features: The Frontier Orbital Bias Dependence at an Exemplar Case of DNA Nucleotides in a Nanogap

et al. 2021

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“…Contrarily, as the bias increases, the WP effect slowly and linearly raises the E HOMO . 38,50 That slow rise is the consequence of two factors: (i) the bias variation of the in-gap electrostatic potential generated by N-C polar bonds from electrode ends, and (ii) the spatial HOMO distribution, centered left with respect to the gap center. 38,50 Thus, while the charge lowers the E HOMO for positive bias, the WP effect raises it linearly, and E HOMO À E F slowly approaches the m R until (at +0.5 V) the two become equal, and further charging with bias stops.…”

Section: The Role Of Oxygen In the Electron Transportmentioning

confidence: 99%

“…The C-N polar bonds generate an in-gap strong electrostatic potential (more than 1 eV per electron) that shifts the molecular HOMO (highest occupied molecular orbital) energy closer to the Fermi energy of electrodes, promoting the hybridization of the probed molecule with electrodes. 30,37,38 In a realistic setting, different molecules can assume different positions in the nanogap between the electrodes. Because of that, we explore the influence of the different in-gap orientations of the TATP molecule on the transport properties.…”

Section: Introductionmentioning

confidence: 99%