58 citations · 550 across the 47 of their papers we have counts for
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Large scale numerical investigation of excited states in poly(phenylene)
Robert J. Bursill, W. Barford
A density matrix renormalisation group scheme is developed, allowing for the first time essentially exact numerical solutions for the important excited states of a realistic semi-e…
The low-lying excitations of polydiacetylene
Alan Race, W. Barford, Robert J. Bursill
The Pariser-Parr-Pople Hamiltonian is used to calculate and identify the nature of the low-lying vertical transition energies of polydiacetylene. The model is solved using the dens…
Excited states of linear polyenes
William Barford, Robert J. Bursill, Mikhail Yu Lavrentiev
We present density matrix renormalisation group calculations of the Pariser- Parr-Pople-Peierls model of linear polyenes within the adiabatic approximation. We calculate the vertic…
Electron-lattice relaxation, and soliton structures and their interactions in polyenes
Robert J. Bursill, William Barford
Density matrix renormalisation group calculations of a suitably parametrised model of long polyenes (polyacetylene oligomers), which incorporates both long range Coulomb interactio…
A theoretical investigation of the low lying electronic structure of poly(p-phenylene vinylene)
Mikhail Yu. Lavrentiev, William Barford, Simon J. Martin +2
The two-state molecular orbital model of the one-dimensional phenyl-based semiconductors is applied to poly(p-phenylene vinylene). The energies of the low-lying excited states are…
Molecular Orbital Models of Benzene, Biphenyl and the Oligophenylenes
R. J. Bursill, W. Barford, H. Daly
A two state (2-MO) model for the low-lying long axis-polarised excitations of poly(p-phenylene) oligomers and polymers is developed. First we derive such a model from the underlyin…
DMRG Calculations of the Low-lying Excitations and Nonlinear Optical Properties of poly(para-phenylene)
W. Barford, R. J. Bursill, M. Yu. Lavrentiev
The two state molecular orbital (2-MO) model of the phenyl based semiconductors is used to calculate the low-lying spectra of the Ag and Bu states of poly(para-phenylene) (PPP). Th…
Charge Transfer Excitons and Possible Exitonic Pairing in the Extended Three Band Hubbard Model
C. Vermeulen, W. Barford, E. R. Gagliano
Exact diagonalisations of the extended Hubbard model are performed. In the insulating regime it is shown that the nearest neighbour copper-oxygen repulsion, , leads to Frenkel e…
A Variational Estimate of the Binding Energy of Charge-Transfer Excitons in the Cuprate Superconductors.
C. Vermeulen, W. Barford
We present a variational estimate for the binding energy of a Frenkel exciton in the insulating cuprate superconductors. Starting from the three band Hubbard model we perform a can…
Phase Separation and Superconductivity in the Copper Oxide Chain
C. Vermeulen, W. Barford, E. R. Gagliano
The phase diagram of the copper-oxide chain as a function of density and the nearest-neighbour Coulomb interaction, V, is determined. Phase separation takes place above a critical…
Strong Coupling Descriptions of High Temperature Superconductors: Electronic Attraction from a Repulsive Potential
W. Barford, M. W. Long
We consider the effect of the nearest neighbour copper-oxygen repulsion, V, when coupled to the charge transfer resonances Cu2+ to Cu3+ and Cu2+ to Cu+ in the high temperature cupr…
Large Phase Separation and Superconductivity in the Copper Oxide Chain
C. Vermeulen, W. Barford, E. R. Gagliano
The phase diagram of the copper-oxide chain as a function of density and the nearest-neighbour Coulomb interaction, V, is determined. Phase separation takes place above a critical…
The Dynamics of the Bean Critical State
W. Barford, W. H. Beere, M. Steer
A simple one dimensional model to simulate the establishment of the Bean critical state is introduced. It is shown that the dynamics of the flux lines as they enter the superconduc…
Incommensurate and Collinear Phases in a Doped Quantum Anti-ferromagnet
W. Barford, S. Jadhav
The Schwinger Boson mean field theories of the `t-J' model are extended by the consideration of anisotropic order parameters. This has two effects. First, a collinear phase, in whi…
Charge Transfer Excitons and the Metal-Insulator Transition in the High Temperature Superconductors
C. Vermeulen, W. Barford, E. R. Gagliano
The effects of the nearest neighbour Coulomb repulsion, V, are considered in the one dimensional copper-oxide chain using the modified Lanczos method. Above a critical value of V w…
The Abrikosov Flux Lattice in Planar Crystals of YBaCuO
M Harrison, W Barford
Anisotropic London Theory is used to predict the Abriskosv flux lattice in planar crystals of YBaCuO. By taking into account the orientation of the flux lattice as a function of ap…