58 citations · 550 across the 47 of their papers we have counts for
21 papers · 1 filter
Nonadiabatic Quantum Dynamics of Hexatriene via the Extended Hubbard-Peierls Model and Time-Dependent DMRG
Timothy N. Georges, Darren J. Valentine, William Barford
Propagating the electronic and nuclear degrees of freedom of a molecule simultaneously is a challenging task, because the number of vibronic states grows exponentially with system…
Triplet-Pair Character of the Dark State of Polyenes
Alexandru G. Ichert, William Barford
We define and calculate the triplet-pair population of the dark state in polyenes, as predicted by the -electron Pariser-Parr-Pople (PPP) model, for chains of 8 to 14 C…
Temperature Dependence of Charge and Exciton Transport in One-Dimensional Systems Subject to Static and Dynamic Disorder
William Barford
The temperature-dependence of dynamical properties (e.g., the asymptotic diffusion coefficient and the sub-diffusive exponent) are calculated for charges and excitons in one-dimens…
A Vibronic Coupling Model to Study the Nonadiabatic Dynamics of Polyenes
Timothy N. Georges, Louis Summerley, Johan E. Runeson +1
We develop a linear vibronic coupling (LVC) model for polyenes described by the extended Hubbard-Peierls Hamiltonian. This model is applied to trans-hexatriene to benchmark quantum…
Singlet Fission in Carotenoid Dimers -- The Role of the Exchange and Dipolar Interactions
Alexandru G. Ichert, William Barford
A theory of singlet fission in carotenoid dimers is presented which aims to explain the mechanism behind the creation of two uncorrelated triplets. Following the initial photoexcit…
Using the Haken-Strobl-Reineker Model to Determine the Temperature Dependence of the Diffusion Coefficient
William Barford
Stochastic quantum Liouville equations (SQLE) are widely used to model energy and charge dynamics in molecular systems. The Haken-Strobl-Reineker (HSR) SQLE is a particular paradig…
Singlet Fission in Lycopene H-Aggregates
William Barford
A theory of singlet fission (SF) in carotenoid dimers is applied to explain the SF in lycopene H-aggregates observed after high energy photoexcitation. The explanation proposed her…
Theory of Singlet Fission in Carotenoid Dimers
William Barford, Cameron A Chambers
We develop a theory of singlet fission in carotenoid dimers. Following photoexcitation of the 'bright' state (i.e., a singlet electron-hole pair) in a single carotenoid, the first…
Photoexcited state dynamics and singlet fission in carotenoids
Dilhan Manawadu, Timothy N. Georges, William Barford
We describe our dynamical simulations of the excited states of the carotenoid, neurosporene, following its photoexcitation into the 'bright' (nominally ) state. We employ…
Dynamical simulations of carotenoid photoexcited states using density matrix renormalization group techniques
Dilhan Manawadu, Darren J. Valentine, William Barford
We present a dynamical simulation scheme to model the highly correlated excited state dynamics of linear polyenes. We apply it to investigate the internal conversion processes of c…
Theory of the Dark State of Polyenes and Carotenoids
William Barford
A theory is developed to describe the singlet dark state (usually labeled S1 or 2Ag) of polyenes and carotenoids. The theory assumes that in principle this state is a linear combin…
Singlet Triplet-Pair Production and Possible Singlet-Fission in Carotenoids
Dilhan Manawadu, Darren Valentine, Max Marcus +1
Internal conversion from the photoexcited state to a correlated singlet triplet-pair state is believed to be the precursor of singlet fission in carotenoids. We present numerical s…
Ultrafast Fluorescence Depolarization in Conjugated Polymers
Isabel Gonzalvez Perez, William Barford
We report on large-scale simulations of intrachain exciton dynamics in poly(para-phenylene vinylene). Our coarse-grained model describes Frenkel exciton coupling to both fast, quan…
Measuring Time-Dependent Induced Quantum Coherences via Two-Dimensional Coherence Spectroscopy
William Barford, Allison Nicole Arber, Fynn McLennan +1
We propose a two-dimensional spectroscopic protocol for measuring the time-dependent coherences between the stationary states of a system induced by a time-dependent system-bath in…
Exciton Dynamics in Conjugated Polymers
William Barford
This is a review of exciton dynamics in conjugated polymers. Exciton dynamics encompass multiple time and length scales. Ultrafast femtosecond processes are intrachain and involve…
Triplet-Triplet Decoherence in Singlet Fission
Max Marcus, William Barford
Singlet fission is commonly defined to involve a process by which an overall singlet state with local triplet structure spin-decoheres into two triplet states, thereby completing t…
Ultra-Fast Relaxation, Decoherence and Localization of Photoexcited States in -Conjugated Polymers: A TEBD Study
Jonathan R. Mannouch, William Barford, Sarah Al-Assam
The exciton relaxation dynamics of photoexcited electronic states in poly(-phenylenevinylene) (PPV) are theoretically investigated within a coarse-grained model, in which both t…
Exciton Transfer Integrals Between Polymer Chains
William Barford
The line-dipole approximation for the evaluation of the exciton transfer integral, , between conjugated polymer chains is rigorously justified. Using this approximation, as well…
Role of Quantum Coherence and Energetic Disorder on Exciton Transport in Polymer Films
William Barford, Christopher D P Duffy
The cross-over from coherent to incoherent exciton transport in disordered polymer films is studied by computationally solving a modified form of the Redfield equation for the exci…
An estimate of the inter-system crossing time in light-emitting polymers
William Barford, Eric E. Moore
The reported enhanced singlet-exciton yields in light-emitting polymers over the statistical limit of 25% has attracted wide experimental and theoretical attention. Most theoretica…
Theory of the singlet exciton yield in light-emitting polymers
William Barford
This paper presents a possible explanation for the enhanced singlet exciton yield in light emitting polymers. We propose a theory of electron-hole recombination via inter-molecular…