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—Staggering computational and algorithmic advances in recent years now make possible systematic Quantum Monte Carlo (QMC) simulations of high temperature (high-Tc) su-perconductivity in a microscopic model, the two dimensional (2D) Hubbard model, with parameters relevant to the cuprate materials. Here we report the algorithmic and computational advances(More)
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)
Crystalline polymorphism of organic semiconductors is among the critical factors in determining the structure and properties of the resultant organic electronic devices. Herein we report for the first time a solvent-type-dependent polymorphism of a long fused-ring organic semiconductor and its crucial effects on charge transport. A new polymorph of(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 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)
The recently synthesized freestanding four-atom-thick double-layer sheet of ZnSe holds great promise as an ultraflexible and transparent photoelectrode material for solar water splitting. In this work, we report theoretical studies on a novel three-atom-thick single-layer sheet of ZnSe that demonstrates a strong quantum confinement effect by exhibiting a(More)
Computational Earth Sciences Group members Tianyu Jiang and Kate Evans published the paper " Intermediate Frequency Atmospheric Disturbances: A Dynamical Bridge Connecting western U.S. Extreme Precipitation with East Asian Cold Surges in linking atmospheric weather extremes " in J. Geophysical Research: Atmospheres with collaborators at Georgia Tech and the(More)
NERSC has partnered with 20 representative application teams to evaluate performance on the Xeon-Phi Knights Landing architecture and develop an application-optimization strategy for the greater NERSC workload on the recently installed Cori system. In this article, we present early case studies and summarized results from a subset of the 20 applications(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)