Escape mechanism of a self-trapped topological soliton

Shin, Yongwoo; Li, Minghai; Botelho, Andre Leitao; Lin, Xi

doi:10.1103/physrevb.82.193101

Cited by 6 publications

(8 citation statements)

References 20 publications

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“…ter λ in its weak-coupling limit [11,12], the SSH Hamiltonian, aided by its derivative Hubbard models for electron correlations, has explained a variety of localization phenomena such as the Peierls instability [13][14][15], Goldstone and amplitude oscillation modes [16,17], dynamic breathers [18], multiple self-localized states [19], and others [7]. Nevertheless, lacking the flexibility to address materials-specific properties of other more stable conducting polymers that are commonly used in practical device applications, the SSH Hamiltonian has been gradually fading out since its heyday in the mid-1980s [7].…”

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confidence: 99%

Unified Hamiltonian for conducting polymers

Botelho¹,

Shin²,

Li³

et al. 2011

J. Phys.: Condens. Matter

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Two transferable physical parameters are incorporated into the Su-Schrieffer-Heeger Hamiltonian to model conducting polymers beyond polyacetylene: the parameter γ scales the electron-phonon coupling strength in aromatic rings and the other parameter ε specifies the heterogeneous core charges. This generic Hamiltonian predicts the fundamental band gaps of polythiophene, polypyrrole, polyfuran, poly-(p-phenylene), poly-(p-phenylene vinylene), and polyacenes, and their oligomers of all lengths, with an accuracy exceeding time-dependent density functional theory. Its computational costs for moderate-length polymer chains are more than eight orders of magnitude lower than first-principles approaches.

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confidence: 99%

Unified Hamiltonian for conducting polymers

Botelho¹,

Shin²,

Li³

et al. 2011

J. Phys.: Condens. Matter

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“…Upon photoexcitation, self-localized electron and hole states reverse the local bond length alternation pattern and therefore the soft bridge bonds are greatly strengthened. 29,30 To account for such a strong coupling between torsions and self-localized polarons and excitons, 29,30 we introduce an analytical switching function in eq 3 so that the local torsional strength dynamically follows the local bond-alternation order parameter 17,22 of…”

Section: ■ Construction Of Assh Hamiltonianmentioning

confidence: 99%

“…15 These nonlinear coupling effects are essential in creating the self-localized solitons and polarons, which are far beyond the harmonic expansion around ground states. 16,17 Third, due to high demands in their computational costs, these DFT-based calculations 10,11 neglecting π−π stacking effects in either of the two phases. Therefore, despite numerous experimental and theoretical investigations, 18−20 the electronic structures and photoinduced electron-transfer mechanisms of these polymer and fullerene heterostructures have not yet been clearly presented.…”

Section: ■ Introductionmentioning

confidence: 99%

Modeling Photoinduced Charge Transfer Across π-Conjugated Heterojunctions

Shin

Lin

2013

J. Phys. Chem. C

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The adapted Su–Schrieffer–Heeger (aSSH) model Hamiltonian is extended in this work to incorporate the interchain π–π stacking and dynamical electron–phonon coupling effects so that the photoinduced charge-transfer mechanism can be directly probed at the π-conjugated heterojunction interfaces. It is found that excitons generated in the bulk poly(p-phenylene vinylene) (PPV) phase require an activation energy of 0.23 eV to reach the heterojunction interfaces before getting their charges separated. Electron transfers from the D1 * state of PPV to the t1u * state of C60 follow the nonadiabatic mechanism, which is accelerated by three major factors including the 0.95 eV energy drop between the two states, close vicinity of the electron-donating D1 * state to the C60 phase, and suppressed inversion symmetry of C60 at the interfaces. The irreversible phonon relaxation energy associated with the nonadiabatic electron transfer is estimated to be 0.3 eV, which explains the widely accepted empirical energy offsets between the measured open-circuit voltage and the theoretical built-in potential.

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“…urally expected to be attractive to charged domain walls, while polymer chain edges were found to be repulsive with an exponentially increasing energy penalty towards the edge. 7 Branching junction structures were known to affect the non-linear dynamics of solitons 9, 10 and often intuitively inferred as molecular-scale electronics. 9,11 For example, Cater has proposed to use a branching junction of trans-polyacetylene (t-PA) as a molecular bifurcation switch, so that after passing the first soliton from one branch through the junction to either of the other two branches with an equal probability of 50%, passing the second soliton should precisely follow the first soliton path with a probability of 100%.…”

Section: Introductionmentioning

confidence: 99%

Self-localized domain walls at π-conjugated branching junctions

Shin

Lin

2011

The Journal of Chemical Physics

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Self-localized domain walls are found trapped at the potential wells created by π-conjugated branching junctions due to the intrinsic electron-phonon couplings. The potential well depths are 0.14 eV for soliton, 0.28 eV for polaron, and 0.32 eV for exciton using the adapted Su-Schrieffer-Heeger model Hamiltonian, as compared to 0.23 eV for soliton, 0.25 eV for positively charged polaron, 0.33 eV for negatively charged polaron, and 0.21 eV for exciton using the ab initio Hartree-Fock method. Once the junction trapping wells are filled, however, branching junctions turn repulsive to additional self-localized domain walls. Torsions around the branching junction center have significant effects on the junction band gap and electron localizations.

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Escape mechanism of a self-trapped topological soliton

Cited by 6 publications

References 20 publications

Unified Hamiltonian for conducting polymers

Unified Hamiltonian for conducting polymers

Modeling Photoinduced Charge Transfer Across π-Conjugated Heterojunctions

Self-localized domain walls at π-conjugated branching junctions

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