P. D. Haynes

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We present ONETEP (order-N electronic total energy package), a density functional program for parallel computers whose computational cost scales linearly with the number of atoms and the number of processors. ONETEP is based on our reformulation of the plane wave pseudopotential method which exploits the electronic localization that is inherent in systems(More)
We present an implementation of time-dependent density-functional theory (TDDFT) in the linear response formalism enabling the calculation of low energy optical absorption spectra for large molecules and nanostructures. The method avoids any explicit reference to canonical representations of either occupied or virtual Kohn-Sham states and thus achieves(More)
Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between(More)
We present progress toward a first-principles parametrization of the Hamiltonian of the Fenna-Matthews-Olson pigment-protein complex, a molecule that has become key to understanding the role of quantum dynamics in photosynthetic exciton energy transfer. To this end, we have performed fully quantum mechanical calculations on each of the seven(More)
Contrary to previous simulation results on the existence of amorphous intergranular films at high-angle twist grain boundaries (GBs) in elemental solids such as silicon, recent experimental results imply structural order in some high-angle boundaries. With a novel protocol for simulating twist GBs, which allows the number of atoms at the boundary to vary,(More)
We present a new method for the calculation of ground-state total energies within density-functional theory, based upon the single-particle density-matrix formulation, which requires a computational eeort which scales only linearly with system-size. The diicult idempotency constraint is imposed approximately using a penalty-functional constructed to allow(More)
ONETEP is an ab initio electronic structure package for total energy calculations within density-functional theory. It combines ‘linear scaling’, in that the total computational effort scales only linearly with system size, with ‘plane-wave’ accuracy, in that the convergence of the total energy is systematically improvable in the manner typical of(More)
We present a detailed comparison between ONETEP, our linear-scaling density functional method, and the conventional pseudopotential plane wave approach in order to demonstrate its high accuracy. Further comparison with allelectron calculations shows that only the largest available Gaussian basis sets can match the accuracy of routine ONETEP calculations.(More)