scholarly journals Modeling the Interplay of Conformational and Electronic Structure in Conjugated Polyelectrolytes

2022 ◽  
Author(s):  
David Friday ◽  
Nicholas Jackson
Keyword(s):  
Electronic Structure ◽  
Electronic Transport ◽  
Tight Binding ◽  
Conformational Space ◽  
Ionic Interactions ◽  
Conjugated Polyelectrolytes ◽  
Single Chain ◽  
Chain Stiffness ◽  
Chain Conformations ◽  
Insight Into

Conjugated polyelectrolytes (CPEs) combine ionic, electronic, and optical functionality with the mechanical and thermodynamic properties of semiflexible, amphiphilic polyelectrolytes. Critical to CPE design is the coupling between macromolecular conformations, ionic interactions, and electronic transport, the combination of which spans electronic to mesoscopic length scales, rendering coherent theoretical analysis challenging. Here, we utilize a recently developed anisotropic CG model in combination with a phenomenological tight-binding Hamiltonian to explore the interplay of single-chain conformational and electronic structure in CPEs. Accessible single chain conformations are explored as a function of solvent conditions and chain stiffness, reproducing a rich landscape of rod-like, racquet, pearl necklace, and helical conformations observed in previous works. The electronic structure of each conformational archtype is further analyzed, incorporating through-bond coupling, through-space coupling, and electrostatic contributions to the Hamiltonian. Electrostatics is observed to influence electronic structure primarily by modifying the accessible conformational space, and only minimally by direct modulation of on-site energies. Electron transport in CPEs is most efficient in helical and racquet conformations, which is attributed to the flattening of dihedrals and through-space coupling within collapsed conformations. Relatedly, kink formation within racquets does not significantly deteriorate electronic conjugation within CPEs - an insight critical to understanding transport within locally ordered aggregates. These conclusions provide unprecedented computational insight into structure function relationships defining emerging classes of CPEs.

scholarly journals Single Chain Mean-Field Theory Study on Responsive Behavior of Semiflexible Polymer Brush

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 778
Author(s):  
Yingli Niu ◽  
Xiangyu Bu ◽  
Xinghua Zhang
Keyword(s):  
Field Theory ◽  
Message Passing Interface ◽  
Mean Field Theory ◽  
Mean Field ◽  
Algorithmic Complexity ◽  
Ensemble Average ◽  
Single Chain ◽  
Metropolis Monte Carlo ◽  
Rigid Rod ◽  
Chain Conformations

The application of single chain mean-field theory (SCMFT) on semiflexible chain brushes is reviewed. The worm-like chain (WLC) model is the best mode of semiflexible chain that can continuously recover to the rigid rod model and Gaussian chain (GC) model in rigid and flexible limits, respectively. Compared with the commonly used GC model, SCMFT is more applicable to the WLC model because the algorithmic complexity of the WLC model is much higher than that of the GC model in self-consistent field theory (SCFT). On the contrary, the algorithmic complexity of both models in SCMFT are comparable. In SCMFT, the ensemble average of quantities is obtained by sampling the conformations of a single chain or multi-chains in the external auxiliary field instead of solving the modified diffuse equation (MDE) in SCFT. The precision of this calculation is controlled by the number of bonds Nm used to discretize the chain contour length L and the number of conformations M used in the ensemble average. The latter factor can be well controlled by metropolis Monte Carlo simulation. This approach can be easily generalized to solve problems with complex boundary conditions or in high-dimensional systems, which were once nightmares when solving MDEs in SCFT. Moreover, the calculations in SCMFT mainly relate to the assemble averages of chain conformations, for which a portion of conformations can be performed parallel on different computing cores using a message-passing interface (MPI).

scholarly journals Indirect bandgap, optoelectronic properties, and photoelectrochemical characteristics of high-purity Ta3N5 photoelectrodes

2021 ◽  
Vol 9 (36) ◽  
pp. 20653-20663
Author(s):  
Johanna Eichhorn ◽  
Simon P. Lechner ◽  
Chang-Ming Jiang ◽  
Giulia Folchi Heunecke ◽  
Frans Munnik ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electronic Properties ◽  
High Purity ◽  
Optoelectronic Properties ◽  
Precise Control ◽  
Insight Into

The (opto)electronic properties of Ta3N5 photoelectrodes are often dominated by defects, but precise control of these defects provides new insight into the electronic structure, photocarrier transport, and photoelectrochemical function.

Tight-Binding Model for DNA Double Chains: Metal–Insulator Transition Due to the Formation of a Double Strand of DNA

1997 ◽  
Vol 11 (20) ◽  
pp. 2405-2423 ◽  
Author(s):  
Kazumoto Iguchi
Keyword(s):  
Electronic Structure ◽  
Finite Temperature ◽  
Deoxyribonucleic Acid ◽  
Recent Observation ◽  
Tight Binding ◽  
Tight Binding Model ◽  
Metal Insulator Transition ◽  
Binding Model ◽  
Metal Insulator ◽  
System A

A tight-binding model is formulated for the calculation of the electronic structure of a double strand of deoxyribonucleic acid (DNA). The theory is applied to DNA with a particular structure such as the ladder and decorated ladder structures. It is found that there is a novel type of metal–insulator transitions due to the hopping anisotropy of the system. A metal-semimetal-semiconductor transition is found in the former and an effective semiconductor-metal transition at finite temperature in the latter, as the effect of base paring between two strands of DNA is increased. The latter mechanism may be responsible for explaining the Meade and Kayyem's recent observation.

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