P. R. C. Kent

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Further developments are introduced in the theory of nite size errors in quantum many{body simulations of extended systems using periodic boundary conditions. We show that our recently introduced Model Periodic Coulomb interaction A. J. Williamson et al., Phys. Rev. B 55, R4851 (1997)] can be applied consistently to all Coulomb interactions in the system.(More)
Diffusion Monte Carlo is a highly accurate Quantum Monte Carlo method for the electronic structure of materials, but it requires frequent load balancing or population redistribution steps to maintain efficiency on parallel machines. This step can be a significant factor affecting performance, and will become more important as the number of processing(More)
A brief overview of the diffusion quantum Monte Carlo method is given. We illustrate the application to ground-state calculations by a study of the relative stability of carbon clusters near the crossover to fullerene stability, thereby determining the smallest stable fullerene. The application to excited states is illustrated via a study of excitonic(More)
The energetic stability of structural isomers of C 24 , C 26 , C 28 , and C 32 clusters, including fullerenes, is studied using diffusion quantum Monte Carlo methods. We predict that a C 24 isomer is the smallest stable graphitic fragment and that the smallest stable fullerenes are the C 26 and C 28 clusters with C 2v and T d symmetry, respectively. Given(More)
Quantum Monte Carlo ͑QMC͒ techniques are used to calculate the one-body density matrix and excitation energies for the valence electrons of bulk silicon. The one-body density matrix and energies are obtained from a Slater-Jastrow wave function with a determinant of local-density approximation ͑LDA͒ orbitals. The QMC density matrix evaluated in a basis of(More)
The emergence of two-dimensional metallic states at the LaAlO3/SrTiO3 (LAO/STO) heterostructure interface is known to occur at a critical thickness of four LAO layers. This insulator to-metal transition can be explained through the "polar catastrophe" mechanism arising from the divergence of the electrostatic potential at the LAO surface. Here, we(More)
Crystalline micrometer-long YSi2 nanowires with cross sections as small as 1 × 0.5 nm(2) can be grown on the Si(001) surface. Their extreme aspect ratios make electron conduction within these nanowires almost ideally one-dimensional, while their compatibility with the silicon platform suggests application as metallic interconnect in Si-based nanoelectronic(More)
We describe a semiempirical method for constructing pseudopotentials for use in correlated wave-function calculations which involves using a combination of calculated and experimental quantities. The pseudopoten-tials are generated from single-valence-electron configurations and satisfy a norm-conservation condition. Core relaxation and core-polarization(More)
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