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

The dielectric and mechanical properties of low permittivity dielectric/metal system consisting of fluoropolymers and copper were studied. The types of polymers in this study include sputtered Teflon, plasma-deposited fluoropolymers and the soluble Teflon AF1600. All these fluoropolymers have dielectric constants below 2.0 and dissipation factors below 0.001. Copper was either evaporated or sputtered. Adhesion of copper to fluoropolymers was studied using scratch and peel tests. Different thermal treatment techniques were applied to enhance adhesion, including preannealing in vacuum or in atmosphere, as well as postannealing in vacuum. The results show generally poor adhesion for evaporated copper, with substantial improvement for sputtered copper; however thermal treatments enhance adhesion in some cases. FTIR, surface tension and XPS experiments were carried out in an effort to understand these effects. Our findings will be discussed in terms of the various effects contributing to copper/fluoropolymer adhesion.

Mechanical and Dielectric Properties of Low Permittivity Dielectric Materials

The refractive indices of In1−xGaxAsyP1−y grown lattice-matched to GaAs by gas-source molecular-beam epitaxy, have been measured by variable angle spectroscopic ellipsometry. Indices in the transparent regime of these quaternaries, at 980 and 808 nm (relevant to the design of pump sources for erbium-doped fiber amplifiers and Nd:YAG lasers, respectively) and at 850 nm, are presented.

Refractive indices of InGaAsP lattice-matched to GaAs at wavelengths relevant to device design

NSERC (Natural Sciences and Engineering Research Council of Canada) industrial research chair on “Low pressure plasma processing of materials”

This paper presents recent scheme based of direct dual wavelength laser writing of lightwave circuits developed in our laboratories. The system allows the fabrication of features of the order of ~1 micron by using a short wavelength laser to ablate a region preheated by a second laser.

Dual laser fabrication of planar lightwave circuits

The base pressure in the chamber was lower than 1.3 10 -5 Pa, while total pressure of N2 and Ar was 1.0 Pa corresponding to a flow of Ar and N2 of 16 and 0.7 sccm, respectively. The Si content in the films was varied by changing the applied power on Si target (PSi) from 50 to 150 W, while maintaining the Ti target power (PTi) at 380 W. The magnetrons were powered from the Pinnacle Plus (Advanced Energy, Inc.) power supply. During the deposition the pulsing frequency (fp) was in the range 50 - 300 kHz with a duty cycle (Dc) in the range 50 – 90%. Negative self-bias voltage, VB, was controlled by the RF (13.56 MHz) power applied to the substrate holder and changing from 0 to 600 V. The films were deposited on silicon substrate at room temperature and at temperature of 300 o C controlled using a spiral-shaped tubular resistive heater. Optical emission spectra (OES) from magnetron and RF discharge were monitored during deposition using the optical emission spectrometer Ocean Optics.

Ludvik Martinu

Papers

Mechanical and Dielectric Properties of Low Permittivity Dielectric Materials

Refractive indices of InGaAsP lattice-matched to GaAs at wavelengths relevant to device design

NSERC (Natural Sciences and Engineering Research Council of Canada) industrial research chair on “Low pressure plasma processing of materials”

Dual laser fabrication of planar lightwave circuits

Effect of substrate bias on the micro- structure and properties of nanocom- posite titanium nitride - based films