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.

Fast parallel algorithms for short-range molecular dynamics

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Metal Oxides and Oxysalts as Anode Materials for Li Ion Batteries

Noble metal nanoparticles are capable of confining resonant photons in such a manner as to induce coherent surface plasmon oscillation of their conduction band electrons, a phenomenon leading to two important properties. Firstly, the confinement of the photon to the nanoparticle's dimensions leads to a large increase in its electromagnetic field and consequently great enhancement of all the nanoparticle's radiative properties, such as absorption and scattering. Moreover, by confining the photon's wavelength to the nanoparticle's small dimensions, there exists enhanced imaging resolving powers, which extend well below the diffraction limit, a property of considerable importance in potential device applications. Secondly, the strongly absorbed light by the nanoparticles is followed by a rapid dephasing of the coherent electron motion in tandem with an equally rapid energy transfer to the lattice, a process integral to the technologically relevant photothermal properties of plasmonic nanoparticles. Of all the possible nanoparticle shapes, gold nanorods are especially intriguing as they offer strong plasmonic fields while exhibiting excellent tunability and biocompatibility. We begin this review of gold nanorods by summarizing their radiative and nonradiative properties. Their various synthetic methods are then outlined with an emphasis on the seed-mediated chemical growth. In particular, we describe nanorod spontaneous self-assembly, chemically driven assembly, and polymer-based alignment. The final section details current studies aimed at applications in the biological and biomedical fields.

Gold Nanorods: From Synthesis and Properties to Biological and Biomedical Applications

Transparent conductors as solar energy materials: A panoramic review

Study of TiO2 film growth mechanisms in low-pressure plasma by in situ real-time spectroscopic ellipsometry

In this work, we propose a fabrication process of a-SiNx:H alloys by pulsing the radio frequency (rf) signal in a low pressure plasma-enhanced chemical vapor deposition (PECVD) system. The characteristics of the films can be controlled simply by adjusting the duty cycle of the pulsed rf power, while keeping the N2∕SiH4 gas mixture constant. Spectroscopic ellipsometry analysis in the ultraviolet-visible-near infrared and far infrared ranges, atomic force microscopy, and elastic recoil detection reveal strong variations in the optical properties (1.88⩽n⩽2.75, 10−4⩽k⩽5×10−2 at 550nm), optical gap (4.01eV⩽Eg⩽1.95eV), microstructural characteristics (1.3nm⩽surfaceroughness⩽8.3nm), and chemical composition (0.47⩽x⩽1.35) of the coatings as a function of duty cycle. This behavior is interpreted in terms of radical concentration changes in the gas phase, as well as variation in the average ion bombardment energy at the film surface, leading to modifications of both chemical and physical mechanisms that sustain the film growth. Using the control of duty cycle, we fabricated two types of a-SiNx:H-based thin film devices, namely, (i) a model Fabry-Perot optical filter deposited on plastic substrate and (ii) a superlattice structure displaying a photoluminescence signal four times higher than the reference single layer. These two examples of applications point out the main advantages of this pulsed rf PECVD process, in particular, low deposition temperature, reproducibility, versatility, and ease of use.

Pulsed radio frequency plasma deposition of a-SiNx:H alloys: Film properties, growth mechanism, and applications

Amorphous hydrogenated silicon-carbide (a-SiC:H) coatings appear very attractive due to their superior optical and mechanical properties and chemical inertness. In the present work a-SiC:H coatings were prepared by PECVD on stainless steel 301 (SS301) and Ti–6Al–4V (TiAlV) substrates at a temperature of 300 °C, using different SiH4/CH4 precursor ratios. We systematically studied such mechanical properties as hardness, reduced Young's modulus and elastic recovery using depth-sensing indentation, their tribological characteristics such as coefficient of friction and wear coefficient using the pin-on-disc method, as well as their corrosion and tribo-corrosion behaviors. a-SiC:H films (∼ 3 μm thick) prepared on SS301 and TiAlV at optimal deposition conditions exhibited a hardness of 23.5 GPa, reduced Young's modulus of 160 GPa, and elastic rebound of 73%. They showed a friction coefficient of ∼ 0.35, and a wear rate of 10 × 10−6 mm3/Nm. These values are low compared to ∼ 0.85 and ∼ 0.5, 240 × 10−6 mm3/Nm and 700 × 10−6 mm3/Nm for SS301 and TiAlV, respectively. The films exhibited a very high corrosion and tribo-corrosion resistance on both metallic substrates. The coating behavior is correlated with the microstructure and composition, determined by complementary characterization techniques including ERD, FTIR and Raman analyses.

Structural, mechanical, tribological, and corrosion properties of a-SiC:H coatings prepared by PECVD

The optical response of Au/SiO2 nanocomposite films at temperatures spanning the transition to the liquid state has been measured. The change in the optical constants of gold from those corresponding to the crystalline material to those of the liquid occurs gradually and at temperatures below the bulk melting point. The similarity of the temperature-induced changes in the Au interband absorption edge to that observed with decreasing particle size suggests that a gradual transition to the liquid phase also occurs in small particles.

Ludvik Martinu

Papers

Study of TiO2 film growth mechanisms in low-pressure plasma by in situ real-time spectroscopic ellipsometry

Pulsed radio frequency plasma deposition of a-SiNx:H alloys: Film properties, growth mechanism, and applications

Structural, mechanical, tribological, and corrosion properties of a-SiC:H coatings prepared by PECVD

Temperature dependence of the surface plasmon resonance of Au/SiO2 nanocomposite films

Quaternary hard nanocomposite TiCxNy/SiCN coatings prepared by plasma enhanced chemical vapor deposition