Christopher F McConville

Bio: Christopher F McConville is an academic researcher from Deakin University. The author has contributed to research in topics: X-ray photoelectron spectroscopy & Band gap. The author has an hindex of 50, co-authored 336 publications receiving 9488 citations. Previous affiliations of Christopher F McConville include University of St Andrews & University of Wolverhampton.

Intrinsic electron accumulation at clean InN surfaces.

Abstract: The electronic structure of clean InN(0001) surfaces has been investigated by high-resolution electron-energy-loss spectroscopy of the conduction band electron plasmon excitations. An intrinsic surface electron accumulation layer is found to exist and is explained in terms of a particularly low Gamma-point conduction band minimum in wurtzite InN. As a result, surface Fermi level pinning high in the conduction band in the vicinity of the Gamma point, but near the average midgap energy, produces charged donor-type surface states with associated downward band bending. Semiclassical dielectric theory simulations of the energy-loss spectra and charge-profile calculations indicate a surface state density of 2.5 (+/-0.2)x10(13) cm(-2) and a surface Fermi level of 1.64+/-0.10 eV above the valence band maximum.

Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In 2 O 3

Abstract: The bulk and surface electronic structure of ${\text{In}}_{2}{\text{O}}_{3}$ has proved controversial, prompting the current combined experimental and theoretical investigation. The band gap of single-crystalline ${\text{In}}_{2}{\text{O}}_{3}$ is determined as $2.93\ifmmode\pm\else\textpm\fi{}0.15$ and $3.02\ifmmode\pm\else\textpm\fi{}0.15\text{ }\text{eV}$ for the cubic bixbyite and rhombohedral polymorphs, respectively. The valence-band density of states is investigated from x-ray photoemission spectroscopy measurements and density-functional theory calculations. These show excellent agreement, supporting the absence of any significant indirect nature of the ${\text{In}}_{2}{\text{O}}_{3}$ band gap. Clear experimental evidence for an $s\text{\ensuremath{-}}d$ coupling between $\text{In}\text{ }4d$ and $\text{O}\text{ }2s$ derived states is also observed. Electron accumulation, recently reported at the (001) surface of bixbyite material, is also shown to be present at the bixbyite (111) surface and the (0001) surface of rhombohedral ${\text{In}}_{2}{\text{O}}_{3}$.

Surface electron accumulation and the charge neutrality level in In2O3.

Abstract: High-resolution x-ray photoemission spectroscopy, infrared reflectivity and Hall effect measurements, combined with surface space-charge calculations, are used to show that electron accumulation occurs at the surface of undoped single-crystalline ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$. From a combination of measurements performed on undoped and heavily Sn-doped samples, the charge neutrality level is shown to lie $\ensuremath{\sim}0.4\text{ }\text{ }\mathrm{eV}$ above the conduction band minimum in ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$, explaining the electron accumulation at the surface of undoped material, the propensity for $n$-type conductivity, and the ease of $n$-type doping in ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$, and hence its use as a transparent conducting oxide material.

Origin of electron accumulation at wurtzite InN surfaces

Abstract: The origin of electron accumulation at wurtzite InN surfaces is explained in terms of the bulk band structure. Ab initio calculations of the electronic structure of wurtzite InN reveal an unusually low conduction band minimum at the $\ensuremath{\Gamma}$-point. As a result, the branch point energy, ${\mathrm{E}}_{B},$ which is the crossover point from donor-type to acceptor-type surface states, is located in the conduction band at the $\ensuremath{\Gamma}$-point. This allows donor-type surface states to exist in the conduction band. The donor-type surface states emit their electrons into the conduction band, thus giving rise to electron accumulation at the surface. Experimental measurements, probing the conduction band electron plasma, confirm the existence of electron accumulation at InN surfaces, with a surface Fermi level location in agreement with the predictions of the ab initio theory.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Preexposure Chemoprophylaxis for HIV Prevention in Men Who Have Sex with Men

Abstract: The study subjects were followed for 3324 person-years (median, 1.2 years; maximum, 2.8 years). Of these subjects, 10 were found to have been infected with HIV at en rollment, and 100 became infected during follow-up (36 in the FTC–TDF group and 64 in the placebo group), indicating a 44% reduction in the incidence of HIV (95% confidence interval, 15 to 63; P = 0.005). In the FTC–TDF group, the study drug was detected in 22 of 43 of seronegative subjects (51%) and in 3 of 34 HIV-infected subjects (9%) (P<0.001). Nausea was reported more frequently during the first 4 weeks in the FTC–TDF group than in the placebo group (P<0.001). The two groups had similar rates of serious adverse events (P = 0.57). Conclusions Oral FTC–TDF provided protection against the acquisition of HIV infection among the subjects. Detectable blood levels strongly correlated with the prophylactic effect. (Funded by the National Institutes of Health and the Bill and Melinda Gates Foun dation; ClinicalTrials.gov number, NCT00458393.)