The Diabatic Picture of Electron Transfer, Reaction Barriers, and Molecular Dynamics

Voorhis, Troy Van; Kowalczyk, Tim; Kaduk, Benjamin; Wang, Lee‐Ping; Cheng, Chiao-Lun; Wu, Qin

doi:10.1146/annurev.physchem.012809.103324

Cited by 296 publications

(369 citation statements)

References 129 publications

(154 reference statements)

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“…42 The objectivity of the diabatization procedure is important because diabatic states are not unique. 32 The insight that can be gained from the structure of any particular diabatic representation is limited by the objectivity of the constraints that define it.…”

Section: A General Discussionmentioning

confidence: 99%

“…This common structure can be discussed in terms of an isolobal analogy. 30, 31 We will show that the isolobal analogy can be exploited to produce a similar isoconfigurational analogy between the many-electron Hilbert spaces of the different dye, and between diabatic 32 representations of the electronic structure. The diabatic states can be identified with the bonding structures invoked in resonance-based theories of the optical response of organic dyes.…”

Section: Introductionmentioning

confidence: 95%

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A three-state effective Hamiltonian for symmetric cationic diarylmethanes

Olsen

McKenzie

2012

The Journal of Chemical Physics

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Comparison of density functionals for energy and structural differences between the high-[ 5 T 2g :(t 2g ) 4 (e g ) 2 ] and low-[ 1 A 1g :(t 2g ) 6 (e g ) 0 ] spin states of iron (II) We analyze the low-energy electronic structure of a series of symmetric cationic diarylmethanes, which are bridge-substituted derivatives of Michler's Hydrol Blue. We use a four-electron, threeorbital complete active space self-consistent field and multi-state multi-reference perturbation theory model to calculate a three-state diabatic effective Hamiltonian for each dye in the series. We exploit an isolobal analogy between the active spaces of the self-consistent field solutions for each dye to represent the electronic structure in a set of analogous diabatic states. The diabatic states can be identified with the bonding structures in classical resonance-theoretic models of cyanine dyes. We identify diabatic states with opposing charge and bond-order localization, analogous to the classical resonance structures, and a third state with charge on the bridge. While the left-and right-charged structures are similar for all dyes, the structure of the bridge-charged diabatic state, and the Hamiltonian matrix elements connected to it, change significantly across the series. The change is correlated with an inversion of the sign of the charge carrier on the bridge, which changes from an electron pair to a hole as the series is traversed.

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Section: A General Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

A three-state effective Hamiltonian for symmetric cationic diarylmethanes

Olsen

McKenzie

2012

The Journal of Chemical Physics

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“…As a rigorous derivation via Eq. 2.20 is involved, approximate constructions, using techniques such as constrained DFT, are preferred [87,88]. The cheapest solution, however, is to approximate the diabatic states via the single-site wave functions |ϕ A ⟩ and |ϕ B ⟩ of the two monomers that participate in the charge transfer.…”

Section: Electronic Couplingsmentioning

confidence: 99%

The (Non-)Local Density of States of Electronic Excitations in Organic Semiconductors

Poelking

2018

Springer Theses

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The (Non-)Local Density of States of Electronic Excitations in Organic Semiconductors The rational design of organic semiconductors for optoelectronic devices relies on a detailed understanding of how their molecular and morphological structure condition the energetics and dynamics of charged and excitonic states. Investigating the role of molecular architecture, conformation, orientation and packing, this work reveals mechanisms that shape the spatially resolved densities of states in organic, small-molecular and polymeric heterostructures and mesophases. The underlying computational framework combines multiscale simulations of the material morphology at atomistic and coarse-grained resolution with a long-range-polarized embedding technique to resolve the electronic structure of the molecular solid. We show that longrange electrostatic interactions tie the energetics of microscopic states to the mesoscopic structure, with a qualitative and quantitative impact on charge-carrier level profiles across organic interfaces. The computational approach provides quantitative access to the charge-density-dependent opencircuit voltage of planar heterojunctions. The derived and experimentally verified relationships between molecular orientation, architecture, level profiles and open-circuit voltage rationalize the acceptor-donor-acceptor pattern for donor materials in high-performing solar cells. Proposing a pathway for barrier-less dissociation of charge transfer states, we highlight how mesoscale fields generate charge splitting and detrapping forces in systems with finite interface roughness. The associated design rules reflect the dominant role played by lowest-energy configurations at the interface. Acknowledgements 121 Die (nicht-)lokale Zustandsdichte elektronischer Anregungen in organischen Halbleitern List of Publications 123Bibliography 125 Chapter 1 Organic Electronics in a NutshellThe discovery of conductive polymers in the 1970s [1,2] -rewarded with the Nobel prize in chemistry in the year 2000 -and subsequent development of the first polymeric electronic devices in the 1980s [3-5] have marked the beginnings of a vast interdisciplinary research field referred to as organic electronics. Drawing from both polymeric and small-molecular semiconductors, organic thin-film transistors, solar cells, light-emitting diodes, photodetectors and sensors name just a few out of many applications that make use of the supreme chemical versatility and mechanical flexibility of the underlying "soft" molecular materials. Furthermore enabling low-temperature solution-based processing, printing and spray coating, organic electronics is set to complement the conventional silicon-based electronics in diverse waysadding functionality and improving sustainability. This introductory chapter will provide a short review of the materials and device physics, as well as of new trends and challenges that emerged in the field over the past decade. MaterialsOrganic semiconductors are molecular materials that exist at the interface between orga...

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“…[4,5] These theories share a common root in the Fermi's Golden Rule result for the transition rate from initial to final state, W if ( = 1 throughout):…”

Section: Introductionmentioning

confidence: 99%

“…The first problem suggests an expansion of diabatic states in an adiabatic basis; the goal is then to determine the adiabaticdiabatic transformation matrix by imposing some criterion for diabatic states, leading to methods such as fragment charge difference, [7] fragment excitation difference, [8,9] Generalized Mulliken-Hush, [10] and state localization. [4,11,12] Alternatively, diabatic states can be produced directly using either constraints on the electronic density [5,13] or valence bond wavefunctions. [14] Both deductive and constructive strategies, however, rely on a somewhat arbitrary set of criteria for diabatization, based on chemical intuition.…”

Section: Introductionmentioning

confidence: 99%

Optimal diabatic bases via thermodynamic bounds

Yeganeh

Voorhis

2011

The Journal of Chemical Physics

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Describing kinetic processes within a perturbation theory approach such as Fermi's Golden Rule requires an understanding of the initial and final states of the system. A number of different methods have been proposed for obtaining these diabatic-like states, but a robust criterion for evaluating their accuracy has not been established. Here, we approach the problem of determining the most appropriate set of diabatic states for use in incoherent rate expressions. We develop a method that rotates an initial set of diabats into an optimized set beginning with a zeroth-order diabatic Hamiltonian and choosing the rotation that minimizes the effect of non-diabatic terms on the thermodynamic free energy. The Gibbs-Bogoliubov (GB) bound on the Helmholtz free energy is thus used as the diabatic criterion. We first derive the GB free energy for a two site system and then find an expression general for any electronic system Hamiltonian. Efficient numerical methods are used to perform the minimization subject to orthogonality constraints, and we examine the resulting diabats for system Hamiltonians in various parameter regimes. The transition from localized to delocalized states is clearly seen in these calculations, and some interesting features are discussed.

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The Diabatic Picture of Electron Transfer, Reaction Barriers, and Molecular Dynamics

Cited by 296 publications

References 129 publications

A three-state effective Hamiltonian for symmetric cationic diarylmethanes

A three-state effective Hamiltonian for symmetric cationic diarylmethanes

The (Non-)Local Density of States of Electronic Excitations in Organic Semiconductors

Optimal diabatic bases via thermodynamic bounds

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