Electronic structure and charge transport properties of atomic carbon wires

Lambropoulos, Konstantinos; Simserides, Constantinos

doi:10.1039/c7cp05134d

Cited by 27 publications

(36 citation statements)

References 51 publications

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“…This condition generalizes for any periodic 1D TB chain the condition reported in [44], where a periodic singlestranded DNA chain with u=4 and symmetric coupling to the leads was studied, with the hopping integrals of the system assumed identical. The method described in this work has been recently implemented for the study of the electronic structure and charge transport properties of atomic carbon wires, confirming and explaining some of the most recent experimental results [46].…”

Section: Introductionsupporting

confidence: 78%

Spectral and transmission properties of periodic 1D tight-binding lattices with a generic unit cell: an analysis within the transfer matrix approach

Lambropoulos

Simserides

2018

J. Phys. Commun.

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We report on the electronic structure, density of states and transmission properties of the periodic one-dimensional tight-binding (TB) lattice with a single orbital per site and nearest-neighbor hoppings, with a generic unit cell of u sites. The determination of the eigenvalues is equivalent to the diagonalization of a real tridiagonal symmetric u-Toeplitz matrix with (cyclic boundaries) or without (fixed boundaries) perturbed upper right and lower left corners. We solve the TB equations via the Transfer Matrix Method, producing analytical solutions and recursive relations for its eigenvalues, closely related to the Chebyshev polynomials. We examine the density of states and provide relevant analytical relations. We attach semi-infinite leads, determine and discuss the transmission coefficient at zero bias and investigate the peaks number and position, and the effect of the coupling strength and asymmetry as well as of the lead properties on the transmission profiles. We introduce a generic optimal coupling condition and demonstrate its physical meaning.

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Section: Introductionsupporting

confidence: 78%

Spectral and transmission properties of periodic 1D tight-binding lattices with a generic unit cell: an analysis within the transfer matrix approach

Lambropoulos

Simserides

2018

J. Phys. Commun.

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“…From a purely theoretical perspective, we expect the trends to be qualitatively independent of molecular length because all three types of wires are isolobal with alternant molecular systems, 39,[114][115] and the change of the electronic structure with length is systematic in finite molecular systems. 70,116 To a certain extent this can be verified with calculations on finite-length molecules. In Figure 10 We note that the Hückel calculations (SI part F) provide further insight into the suppression of the transmission in even-n cumulenes due to destructive quantum interference.…”

Section: Even-n Cumulenic Carbon Wiresmentioning

confidence: 66%

Three Distinct Torsion Profiles of Electronic Transmission Through Linear Carbon Wires

Garner

Bro-Jørgensen²,

Solomon³

2020

Preprint

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The one-dimensional carbon allotrope carbyne, a linear chain of sp-hybridized carbon atoms, is predicted to exist in a polyynic and a cumulenic structure. While molecular forms of carbyne have been extensively characterized, the structural nature is hard to determine for many linear carbon wires that are made in-situ during pulling experiments. Here, we show that cumulenes and polyynes have distinctively different low-bias conductance profiles under axial torsion. We analyze the change of the electronic structure, Landauer transmission, and ballistic current density of the three types of closed-shell molecular carbynes as a function of the torsion angle. Both polyynic, odd-carbon cumulenic, and even-carbon cumulenic carbon wires exhibit helical frontier molecular orbitals when the end-groups are not in a co-planar configuration. This helical conjugation effect gives rise to strong ring current patterns around the linear wires. Only the transmission of even-carbon polyynic wires follows the well-known cosine-squared law with axial torsion that is also seen in biphenyl-type systems. Notably, the transmission of even-carbon cumulenic carbon wires rises with axial torsion from co-planar towards perpendicular orientation of the end-groups. The three distinct transmission profiles of polyynes, odd-carbon cumulenes, and even-carbon cumulenes may allow for experimental identification of the structural nature of linear carbon wires. Their different electron transport properties under axial torsion furthermore underline that, in the molecular limit of carbyne, three different subclasses of linear carbon wires exist.

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“…In TBI,

and

. Details and discussions of various aspects of the TBI wire model can be found elsewhere [ 5 , 33 , 34 , 35 , 36 , 37 ]. In TBImod,

and

.…”

Section: Tight-binding Wire Model Variantsmentioning

confidence: 99%

“…We discriminate between the terms transport and transfer: transport implies application of electric voltage between electrodes connected at the ends of the system; transfer implies that an extra electron or hole, created, e.g., by reduction or oxidation at a certain site, moves to more favorable sites, without application of external voltage. Experimental [ 1 , 2 , 3 , 4 ] as well as theoretical work [ 5 , 6 , 7 , 8 , 9 ] on charge transport in carbynes has been accomplished. However, it seems that there is no experiment of charge transfer along these molecules, apart from a very recent work [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Hole Transfer in Open Carbynes

2020

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We investigate hole transfer in open carbynes, i.e., carbon atomic nanowires, using Real-Time Time-Dependent Density Functional Theory (RT-TDDFT). The nanowire is made of N carbon atoms. We use the functional B3LYP and the basis sets 3-21G, 6-31G*, cc-pVDZ, cc-pVTZ, cc-pVQZ. We also utilize a few Tight-Binding (TB) wire models, a very simple model with all sites equivalent and transfer integrals given by the Harrison ppπ expression (TBI) as well as a model with modified initial and final sites (TBImod) to take into account the presence of one or two or three hydrogen atoms at the edge sites. To achieve similar site occupations in cumulenes with those obtained by converged RT-TDDFT, TBImod is sufficient. However, to achieve similar frequency content of charge and dipole moment oscillations and similar coherent transfer rates, the TBImod transfer integrals have to be multiplied by a factor of four (TBImodt4times). An explanation for this is given. Full geometry optimization at the B3LYP/6-31G* level of theory shows that in cumulenes bond length alternation (BLA) is not strictly zero and is not constant, although it is symmetrical relative to the molecule center. BLA in cumulenic cases is much smaller than in polyynic cases, so, although not strictly, the separation to cumulenes and polyynes, approximately, holds. Vibrational analysis confirms that for N even all cumulenes with coplanar methylene end groups are stable, for N odd all cumulenes with perpendicular methylene end groups are stable, and the number of hydrogen atoms at the end groups is clearly seen in all cumulenic and polyynic cases. We calculate and discuss the Density Functional Theory (DFT) ground state energy of neutral molecules, the CDFT (Constrained DFT) “ground state energy” of molecules with a hole at one end group, energy spectra, density of states, energy gap, charge and dipole moment oscillations, mean over time probabilities to find the hole at each site, coherent transfer rates, and frequency content, in general. We also compare RT-TDDFT with TB results.

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Electronic structure and charge transport properties of atomic carbon wires

Cited by 27 publications

References 51 publications

Spectral and transmission properties of periodic 1D tight-binding lattices with a generic unit cell: an analysis within the transfer matrix approach

Spectral and transmission properties of periodic 1D tight-binding lattices with a generic unit cell: an analysis within the transfer matrix approach

Three Distinct Torsion Profiles of Electronic Transmission Through Linear Carbon Wires

Hole Transfer in Open Carbynes

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