Research Guides

Electronic and Optical Processes in Macromolecular Systems

Conjugated molecules (e.g. polymers, nanotubes, porphyrins and DNA) occur widely in many biological and synthetic systems (e.g. polymer optoelectronic devices, light harvesting complexes and cells).

They are characterised by strong electron-electron and electron-phonon interactions. My research is primarily focussed on understanding the effect of these interactions on the electronic properties of conjugated molecular systems and their associated electronic processes.

A further aim is to predict how the electronic and optical behaviour of condensed phases is determined by the multi-scale structures of the component molecules. These goals are being pursued using a variety of theoretical methods and computational techniques (e.g. DMRG and CI-S).

Recent work is listed below under "Selected Publications".

I am a member of the Oxford Theoretical Chemistry Group and a tutorial fellow in Physical Chemistry at Balliol College.

My current projects include:

• Modelling exciton dynamics in conjugated polymers.

• Developing and computing theoretical models of electronic processes in conjugated polymers.

• Developing the density matrix renormalization group (DMRG) method for quantum chemistry and condensed matter physics.

• Investigating quantum phase transitions in one-dimensional strongly coupled electron-phonon systems.
  

• Understanding photosynthesis and photo-protection mechanisms in light harvesting complexes.

Exciton Localization in Disordered Conjugated Polymers

Exciton localization in disordered poly(3-hexylthiophene), W. Barford, D. G. Lidzey, D. V. Makhov, and A. J. H. Meijer, J. Chem. Phys. 133, 44504 (2010).

Local exciton ground states in disordered polymers, D. V. Makhov and W. Barford, Phys. Rev. B 81, 165201 (2010).

Exciton localization in polymers with static disorder, W. Barford and D. Trembath, Phys. Rev. B 80, 165418 (2009).

Electronic Processes in Conjugated Polymers

Beyond Förster resonance energy transfer in linear nanoscale systems, W. Barford, J. Phys. Chem. A. 114, 11842 (2010).

Spin-orbit interactions between inter-chain excitations in conjugated polymers, W. Barford, R. J. Bursill, and D. V. Makhov, Phys. Rev. B 81, 35206 (2010).

Exciton transfer integrals between polymer chains, W. Barford, J. Chem. Phys. 126, 134905 (2007).

Theory of the singlet exciton yield in light emitting polymers, W. Barford, Phys Rev B 70, 205204 (2004).

Excited State Properties of Conjugated Polymers

Symmetry-adapted density matrix renormalization group calculations of the primary excited states of poly(p-phenylene vinylene), R. J. Bursill and W. Barford, J. Chem. Phys. 130, 234302 (2009).

Excitons in conjugated polymers: wavefunctions, symmetries and quantum numbers, W. Barford and N. Paiboonvorachat, J. Chem. Phys. 129, 164716 (2008).

Quantum Phase Transitions in One Dimensional Systems

Quantized lattice dynamic effects on the Peierls transition of the extended Hubbard model, C. J, Pearson, W. Barford, and R. J. Bursill (submitted).

Quantized lattice dynamic effects on the spin-Peierls transition, C. J. Pearson, W. Barford, and R. J. Bursill, Phys. Rev. B 82, 144408 (2010).

Peierls transition in the quantum spin-Peierls model, W. Barford and R. J. Bursill, Phys. Rev. Lett. 95, 137207 (2005).

Book

Electronic and Optical Properties of Conjugated Polymers, W. Barford, Oxford University Press (2005).